Comparison of perioperative outcomes between gasless transaxillary endoscopic thyroidectomy and conventional open thyroidectomy for papillary thyroid carcinoma: a retrospective study

Introduction

Thyroid cancer has become one of the most common malignancies in China in terms of incidence, among which differentiated thyroid carcinoma (DTC) accounts for the vast majority of all thyroid cancers. In recent years, with the widespread use of imaging techniques and the continuous improvement in population-based health screening, the detection rate of DTC has shown a persistent upward trend, which is particularly pronounced in women and demonstrates a clear sex disparity (1,2). According to authoritative domestic and international guidelines, surgical resection remains the primary and most effective treatment for DTC and is the key approach to achieving curative tumor control (3). Conventional open thyroidectomy (COT) is usually performed through a transverse cervical incision in the anterior neck. This technique is well established, provides ample operative exposure, and has a high safety profile, and therefore has long been regarded as the standard procedure in thyroid surgery. However, the residual anterior neck scar may adversely affect patients’ cosmetic satisfaction and long-term quality of life, especially in those who are prone to hypertrophic scarring or have high cosmetic expectations (4). Therefore, while ensuring oncological radicality, how to balance surgical safety with postoperative cosmetic outcomes has become an important research focus in the field of thyroid surgery.

The development of endoscopic thyroid surgery can be traced back to 1996, when Gagner first applied endoscopic techniques to cervical endocrine surgery, opening a new era in minimally invasive thyroid surgery. Shortly thereafter, Hüscher et al. successfully performed the first endoscopic thyroidectomy, further confirming the feasibility of this technique (5,6). Subsequently, scholars such as Miccoli and Shimizu further advanced minimally invasive thyroid surgery by introducing various endoscopic-assisted and totally endoscopic procedures (7,8). With the growing acceptance of minimally invasive concepts and the maturation of endoscopic techniques, several remote-access approaches have been proposed and gradually introduced into clinical practice, mainly including the breast approach, transaxillary approach, supraclavicular approach, and transoral vestibular approach (9,10). A common feature of these procedures is that the incisions are placed in relatively concealed areas of the body surface, thereby significantly improving postoperative cosmetic outcomes and enhancing patient satisfaction while still achieving oncological treatment goals (11). Among them, transoral endoscopic thyroidectomy via vestibular approach (TOETVA), as a truly scarless procedure without any visible external incision, has also gradually matured in recent years and has become one of the major research topics in thyroid surgery (12).

Among the various endoscopic approaches, the transaxillary approach has been widely adopted because of its relatively established operative pathway, clear anatomical planes, and comparatively shorter learning curve. In particular, gasless transaxillary endoscopic thyroidectomy (GUA) creates the operative space using a specially designed mechanical retractor, thereby avoiding complications related to CO₂ insufflation, such as subcutaneous emphysema and hypercapnia (13). According to the recommendations of the Chinese Expert Consensus on Gasless Transaxillary Endoscopic Thyroid Surgery (2022 Edition), this procedure is mainly suitable for patients with low-risk thyroid cancer characterized by small tumor size and no extensive lymph node metastasis, and it should be performed in centers with appropriate technical expertise and experience to ensure surgical safety and therapeutic efficacy (14). Notably, the same consensus also points out that the transaxillary approach is generally not recommended, or should be selected with caution, in obese patients or those with well-developed neck musculature, because these factors may increase the difficulty of workspace creation and operative manipulation. However, in actual clinical practice, some surgeons have observed that in such patients undergoing transaxillary endoscopic surgery, the thicker subcutaneous fat layer and relatively easier maintenance of the operative space may, to some extent, facilitate surgical exposure and instrument handling, thereby making the operation smoother. This discrepancy between “guideline recommendations” and “clinical experience” suggests that the actual impact of individual factors such as body mass index (BMI) on endoscopic surgery still requires further objective evaluation and also provides a practical rationale for the present study. Previous clinical studies have confirmed that this procedure is comparable to conventional open surgery in terms of oncological radicality and postoperative complication rates (15,16), while offering significant advantages in postoperative cosmetic outcomes and patient satisfaction (17).

Nevertheless, because endoscopic surgery involves a relatively complex process of workspace creation, a longer operative route, and a steeper learning curve, its perioperative outcomes compared with those of conventional open surgery remain controversial (18). Some studies have suggested that although endoscopic surgery provides superior cosmetic results, it is associated with longer operative time, higher hospitalization costs, and possibly greater postoperative drainage volume; other studies, however, have indicated that endoscopic surgery may be associated with less postoperative pain, faster recovery, and better quality of life (19). Therefore, further large-sample clinical studies are warranted to systematically compare perioperative outcomes between different surgical approaches and to provide more robust evidence for clinical decision-making regarding surgical approach selection.

In addition, the choice of surgical approach for thyroid cancer is influenced by a combination of multiple clinical factors. Previous studies have mainly focused on tumor-related factors, such as tumor size, location, multifocality, and lymph node metastasis (20). In recent years, with the deepening understanding of metabolic factors, BMI, as an important metabolic indicator, has gradually attracted increasing attention. Some studies have suggested that BMI may be associated with tumor aggressiveness and surgical difficulty in thyroid cancer (21,22). At the same time, obesity-related chronic inflammation and metabolic abnormalities may also influence tumor initiation and progression through multiple molecular mechanisms (23-26). However, current studies on the relationship between BMI and perioperative outcomes of thyroid surgery have not reached consistent conclusions, and whether BMI should be considered an important reference factor in surgical approach selection remains to be further clarified.

Based on the above background, the present study was designed as a retrospective cohort study to compare perioperative outcomes between GUA and COT, to further analyze their patterns across different BMI strata, and to explore the relationship between BMI and perioperative indicators, with the aim of providing evidence to support individualized surgical strategies in clinical practice. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0209/rc).

Methods

Study design

This study was designed as a single-center retrospective cohort study. Clinical data were retrospectively collected from patients who underwent thyroid surgery at the Affiliated Huzhou Hospital of Zhejiang University between October 1, 2023 and October 1, 2024 and were postoperatively confirmed by pathology to have papillary thyroid carcinoma (PTC). A total of 948 patients were initially screened, and after applying the predefined inclusion and exclusion criteria, 411 patients were ultimately enrolled in the study (the detailed screening process is shown in Figure 1).

Figure 1 Flowchart of patient enrollment in the study. COT, conventional open thyroidectomy; FNA, fine-needle aspiration; GUA, gasless transaxillary endoscopic thyroidectomy.

The aim of this study was to compare perioperative outcomes between GUA and COT in patients with PTC, and to further analyze the patterns of perioperative indicators associated with these two surgical approaches across different BMI strata. In addition, the relationships of BMI and related clinicopathological factors with perioperative indicators and pathological N stage (pN) were explored, in order to provide clinical evidence for surgical approach selection and perioperative management in patients with PTC.

Ethics statement

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Huzhou Central Hospital (approval No. 202506022-01). As this was a retrospective study and involved no additional intervention in patients’ diagnostic or therapeutic management, the requirement for informed consent was waived by the Ethics Committee. All included data were anonymized and used exclusively for the purposes of this study.

Study content and follow-up indicators

Preoperative evaluation and preparation

• After admission, patients’ basic information was first recorded, including sex, age, history of hypertension, history of diabetes mellitus, and other major comorbidities. A detailed surgical history was also obtained.
• Thyroid-related examinations:
  • All patients underwent thyroid ultrasonography, with findings assessed according to the TI-RADS classification. The number, location, maximum diameter, and internal characteristics of thyroid nodules were recorded. When necessary, cervical computed tomography (CT) was performed to assist in preoperative evaluation. Fine-needle aspiration (FNA) biopsy of the thyroid was also conducted.
  • During hospitalization, thyroid function-related laboratory tests were completed, including thyroid peroxidase antibody, thyroglobulin antibody, and a five-item thyroid function panel comprising free triiodothyronine (FT3), free thyroxine (FT4), triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH).
• In addition, routine preoperative examinations included complete blood count, serum electrolytes, coagulation function, liver and renal function tests, the four routine preoperative infectious disease screening items, routine urine and stool tests, electrocardiography, chest radiography, and electronic laryngoscopy. For patients older than 60 years, further cardiac function evaluation and echocardiography were performed.
• The principle of informed consent was strictly followed. Before surgery, the patients and their family members were informed of the disease condition, and the procedures and clinical significance of conventional open surgery and transaxillary endoscopic surgery were explained in detail. Possible intraoperative and postoperative complications, as well as their corresponding management strategies, were also discussed, together with the timing and content of postoperative follow-up. Surgery was performed only after the patients and their family members had fully understood the relevant information and signed the informed consent form for surgery.

Grouping

• Surgical approach grouping: patients were divided into the COT group and the GUA group according to the surgical procedure they underwent.
• BMI grouping: according to the World Health Organization (WHO) classification criteria for Asian populations, patients were categorized into three BMI subgroups: the underweight group (<18.5 kg/m²), the normal-weight group (18.5–22.9 kg/m²), and the overweight/obese group (≥23.0 kg/m²).

Surgical procedure for conventional open unilateral radical thyroidectomy for thyroid carcinoma

• After successful induction of general anesthesia, the patient was placed in the supine position, with a pad placed under the shoulders to achieve full neck extension, and the surgical landmarks were marked on the body surface (Figure 2).
  

  Figure 2 Schematic illustration of the COT incision. COT, conventional open thyroidectomy.
• Routine skin disinfection and sterile draping were then performed. Subsequently, a diluted ropivacaine solution containing 1:200,000 epinephrine was injected subcutaneously into the planned incision area. Approximately 5 minutes later, a curved incision was made along the natural skin crease about two fingerbreadths above the sternal notch. The skin, subcutaneous tissue, and platysma were incised sequentially, and subplatysmal flaps were elevated superiorly and inferiorly.
• The linea alba cervicalis and the thyroid surgical capsule were incised, and the strap muscles were retracted to expose the operative field and fully reveal the thyroid gland. Dissection was performed along the true capsule of the gland using meticulous capsular dissection. The relevant branches of the inferior thyroid vessels, middle thyroid vein, and superior thyroid vessels were divided and ligated using an ultrasonic scalpel. During the procedure, meticulous dissection was carried out to actively identify and preserve the superior and inferior parathyroid glands and their blood supply, while also exposing and protecting the recurrent laryngeal nerve. After resection of the affected thyroid lobe and isthmus, the specimen was inspected to confirm the absence of obvious parathyroid tissue and was then sent for intraoperative frozen-section examination.
• Central compartment lymph node dissection was then performed. According to guideline recommendations, the boundaries of central neck dissection were defined as follows: the superior border at the level of the hyoid bone, the inferior border at the upper edge of the innominate artery, and the lateral border at the medial edge of the common carotid artery. Lymph nodes and fibro-fatty connective tissue in the pretracheal, prelaryngeal, and paratracheal regions along the recurrent laryngeal nerve were removed en bloc. Throughout the central compartment dissection, every effort was made to preserve the parathyroid glands and their vascular supply in situ. If in situ preservation was deemed impossible, parathyroid autotransplantation was performed.
• Finally, the operative field was irrigated with distilled water. After meticulous hemostasis, a negative-pressure drainage tube was placed, and the incision was closed layer by layer after the instrument count had been confirmed to be correct.

Surgical procedure for gasless transaxillary endoscopic unilateral radical thyroidectomy for thyroid carcinoma

• After successful induction of general anesthesia, the patient was placed in the supine position. An intraoperative neural monitoring system was established by percutaneous placement of nerve monitoring electrodes. The head was extended and slightly turned to the contralateral side, the ipsilateral upper limb was abducted, and the surgical landmarks were marked on the body surface (Figure 3).
  

  Figure 3 Schematic illustration of the GUA incision. GUA, gasless transaxillary endoscopic thyroidectomy.
• Routine skin disinfection and sterile draping were then performed. Subsequently, a diluted ropivacaine solution containing 1:200,000 epinephrine was injected subcutaneously into the planned incision area. Approximately 5 minutes later, an incision was made along the natural skin crease in the ipsilateral axilla, and the skin and subcutaneous tissue were incised layer by layer to expose the lateral border of the pectoralis major muscle.
• The flap was further dissected along the surface of the pectoralis major muscle. The clavicular and sternal heads of the sternocleidomastoid muscle were separated to open the interval between them, with care taken to protect the internal jugular vein. The omohyoid muscle and sternothyroid muscle were then exposed and separated to allow adequate exposure of the thyroid gland.
• A retractor was placed behind the sternothyroid muscle for suspension, thereby creating the working space for endoscopic surgery. Under direct endoscopic vision, the lateral aspect of the thyroid gland was dissected along the true capsule using meticulous capsular dissection. Branches of the superior and inferior thyroid vessels, as well as the middle thyroid vein, were divided using an ultrasonic scalpel. During the procedure, careful attention was paid to identifying and preserving the right parathyroid glands and their blood supply. Meanwhile, the intraoperative neural monitoring system was used to record the V1 signal of the vagus nerve and the R1 signals of the recurrent laryngeal nerve and superior laryngeal nerve, in order to ensure neural integrity. With the relevant neural structures adequately protected, the thyroid lobe, isthmus, and prelaryngeal tissue were completely resected and removed en bloc in a specimen retrieval bag. The specimen was inspected and showed no obvious parathyroid tissue, and was then sent for intraoperative frozen-section examination.
• Central compartment lymph node dissection was then performed. According to guideline recommendations, the boundaries of central neck dissection were the same as those described above, and lymph nodes together with fibro-fatty connective tissue in the pretracheal, prelaryngeal, and paratracheal regions along the recurrent laryngeal nerve were removed en bloc. If any parathyroid gland could not be preserved in situ, autotransplantation was performed. After completion of the central compartment dissection, the V2 signal of the vagus nerve and the R2 signal of the recurrent laryngeal nerve were recorded again using the neural monitoring system, with no significant decrease observed compared with the pre-dissection signals.
• Finally, the operative field was irrigated in a compartmental manner with distilled water. After meticulous hemostasis, a negative-pressure drainage tube was placed, and the incision was closed layer by layer after the instrument count had been confirmed to be correct.

Data collection

Preoperative data included age, sex, height, weight, BMI, past medical history, preoperative BRAF mutation status, and preoperative ultrasonographic findings.

Intraoperative data included the date of surgery, operative time, and intraoperative blood loss.

Postoperative data included the number of dissected lymph nodes, postoperative pN, total postoperative drainage volume, postoperative complications, date of discharge, postoperative length of hospital stay, total length of hospital stay, and total hospitalization cost. Postoperative complications included postoperative bleeding, incision infection, lymphatic leakage, symptoms suggestive of recurrent laryngeal nerve injury such as transient hoarseness, and symptoms related to postoperative hypoparathyroidism.

Post-discharge follow-up was performed by telephone at 3 months after surgery to assess cosmetic satisfaction with the surgical incision. Cosmetic satisfaction was scored using a 4-point scale: 1 point indicated dissatisfaction, defined as dissatisfaction with scar recovery, such as itching, hypertrophic scarring, or poor cosmetic appearance; 2 points indicated neutral satisfaction, defined as an acceptable but not clearly satisfactory scar appearance; 3 points indicated satisfaction, defined as scar recovery meeting the patient’s expectations; and 4 points indicated very high satisfaction, defined as scar recovery fully meeting or exceeding the patient’s expectations. For further analysis, patients with scores of 3 or 4 were classified as cosmetically satisfied, whereas those with scores of 1 or 2 were classified as not cosmetically satisfied.

Inclusion criteria

• Age ≥18 years.
• Patients undergoing their first thyroid surgery at the Affiliated Huzhou Hospital of Zhejiang University.
• Complete data availability, including full clinical records and postoperative pathological data.
• Postoperative pathological confirmation of PTC.
• Tumor diameter ≤3 cm, with no extrathyroidal extension on imaging or gross examination, and no clinical evidence of lymph node metastasis (cN0).
• Unilateral radical thyroidectomy was performed, defined as unilateral lobectomy with isthmusectomy and ipsilateral central compartment lymph node dissection, using either the conventional open approach or the transaxillary endoscopic approach.

Exclusion criteria

• History of previous neck surgery.
• Presence of severe systemic diseases, such as severe hypertension, diabetes mellitus, renal insufficiency, or coagulation disorders.
• Preoperative identification of high-risk features of thyroid cancer, including:
  • Extrathyroidal extension;
  • Clinically evident locoregional or distant metastasis;
  • History of head and neck irradiation;
  • Positive family history of thyroid cancer.
• Uncontrolled hyperthyroidism or hypothyroidism.
• History of other malignant tumors.
• Pregnant or lactating women.
• Incomplete key data.

Statistical analysis

All data were processed and analyzed using SPSS version 27.0.

In this study, continuous variables were first tested for normality. Continuous variables that conformed to a normal distribution (P>0.05) were expressed as mean ± standard deviation (mean ± SD), and comparisons between groups were performed using the independent-samples t-test. Continuous variables that did not conform to a normal distribution (P<0.05) were expressed as median and interquartile range [M (Q1–Q3)], and comparisons between groups were performed using the Mann-Whitney U test. Categorical variables were expressed as number (percentage), and comparisons between groups were conducted using the χ² test. All statistical tests were two-sided, and a P value <0.05 was considered statistically significant.

Spearman’s rank correlation analysis was performed for variables including sex, age, BMI, preoperative nodule size, number of dissected lymph nodes, operative time, postoperative drainage volume, postoperative pN, postoperative length of hospital stay, and total hospitalization cost.

To further explore the factors associated with postoperative pN, pN stage was used as the dependent variable, and univariable as well as multivariable binary logistic regression analyses were performed. Variables entered into the model included sex, age, BMI, preoperative nodule size, and other variables that were either clinically relevant or found to be statistically significant in the univariable analysis. All statistical tests were two-sided, and a P value <0.05 was considered statistically significant.

Results

Comparison of baseline characteristics between the two groups

A total of 411 patients with PTC were included in this study, of whom 144 (35.0%) underwent GUA (GUA group) and 267 (65.0%) underwent COT (COT group). Detailed comparisons of baseline characteristics between the two groups are presented in Table 1.

With regard to age distribution, the mean age of patients in the GUA group was 36.59±8.89 years, with a median age of 35.00 (30.00–42.00) years, whereas the mean age in the COT group was 47.62±12.05 years, with a median age of 49.00 (37.00–56.00) years; the difference between the two groups was statistically significant (P<0.001).

In terms of sex, the GUA group included 28 male patients (19.4%) and 116 female patients (80.6%), while the COT group included 78 male patients (29.2%) and 189 female patients (70.8%). The sex distribution differed significantly between the two groups (P=0.03).

According to BMI classification, the GUA group comprised 6 underweight patients (4.2%), 82 normal-weight patients (56.9%), and 56 overweight patients (38.9%), whereas the COT group comprised 10 underweight patients (3.7%), 134 normal-weight patients (50.2%), and 123 overweight patients (46.1%). No statistically significant difference in BMI distribution was observed between the two groups (P=0.38).

Regarding tumor characteristics, the mean nodule diameter in the GUA group was 6.098±3.265 mm, which was smaller than that in the COT group (7.008±3.824 mm), and the difference was statistically significant (P=0.01). As for BRAF mutation status, 96 patients (66.7%) in the GUA group were BRAF-positive, 12 (8.3%) were BRAF-negative, and 36 (25.0%) were untested; the corresponding numbers in the COT group were 153 (57.3%), 21 (7.9%), and 93 (34.8%), respectively. No statistically significant difference was found between the two groups (P=0.12).

Comparison of perioperative outcomes between different surgical approaches

With regard to surgery-related indicators (Table 2), the median operative time in the GUA group was 90.00 (80.00–110.00) min, which was longer than that in the COT group [70.00 (60.00–85.00) min], and the difference was statistically significant (P<0.001). For the number of central compartment lymph nodes dissected, the median number in the GUA group was 4 (2–5), which was lower than that in the COT group [5 (3–8)], with a statistically significant difference (P<0.001). Regarding pN stage, 86 patients (59.7%) in the GUA group were classified as pN0 and 58 (40.3%) as pN1, whereas in the COT group, 181 patients (67.8%) were classified as pN0 and 86 (32.2%) as pN1. No statistically significant difference was observed between the two groups (P=0.10).

With respect to postoperative recovery and health economic indicators, the median postoperative drainage volume in the GUA group was 110.00 (90.00–135.00) mL, which was higher than that in the COT group [65.00 (50.00–80.00) mL], and the difference was statistically significant (P<0.001). The median postoperative length of hospital stay was 2.00 days in both groups. Although the difference reached statistical significance (P=0.02), the clinical difference was small. In terms of total hospitalization cost, the median cost in the GUA group was 16,712 (15,594–18,376) CNY, which was higher than that in the COT group [12,282 (12,016–12,829) CNY], and the difference was statistically significant (P<0.001).

Comparison of perioperative indicators across BMI strata

Given that BMI may influence the technical difficulty of thyroid surgery as well as perioperative indicators, stratified analyses were further performed according to BMI category in this study to compare perioperative outcomes between the two surgical approaches at different BMI levels. The detailed results are as follows.

Underweight group

The BMI-stratified analysis showed that among underweight patients (Table 3), the operative time was 88.83±26.65 min in the GUA group and 82.10±20.02 min in the COT group, with no statistically significant difference (P=0.57). The postoperative drainage volume in the GUA group was 120.00±36.74 mL, which was significantly higher than that in the COT group (76.00±18.37 mL), and the difference was statistically significant (P=0.006). No statistically significant differences were observed between the two groups in the number of dissected lymph nodes or postoperative length of hospital stay (both P>0.05). In terms of total hospitalization cost, the GUA group had a significantly higher cost than the COT group (16,350.83±2,318.14 vs. 12,522.23±1,614.96 CNY, P=0.002).

Normal-weight group

Among normal-weight patients (Table 4, Figures 4-6), the median operative time in the GUA group was 90.00 (76.50–106.25) min, which was longer than that in the COT group [70.00 (58.00–90.00) min], and the difference was statistically significant (P<0.001). The median postoperative drainage volume in the GUA group was 105.00 (85.00–126.25) mL, which was higher than that in the COT group [60.00 (50.00–75.00) mL], with a statistically significant difference (P<0.001). Regarding the number of dissected lymph nodes, the median number in the GUA group was 4.0 (2.0–6.0), which was lower than that in the COT group [5.0 (3.0–8.0)], and the difference was statistically significant (P=0.001). A statistically significant difference was also observed in postoperative length of hospital stay between the two groups (P=0.02). In terms of total hospitalization cost, the GUA group had a median cost of 16,610.23 (15,618.42–18,295.27) CNY, which was significantly higher than that in the COT group [12,336.79 (12,015.65–12,944.10) CNY], and the difference was statistically significant (P<0.001).

Figure 4 Operative time in the normal-weight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

Figure 5 Postoperative drainage volume in the normal-weight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

Figure 6 Number of dissected lymph nodes in the normal-weight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

Overweight group

Among overweight patients (Table 5, Figures 7-9), the median operative time in the GUA group was 90.00 (80.50–111.50) min, which was longer than that in the COT group [70.00 (60.00–85.00) min], and the difference was statistically significant (P<0.001). The median postoperative drainage volume in the GUA group was 110.00 (90.00–145.00) mL, which was higher than that in the COT group [67.00 (55.00–85.00) mL], and the difference was statistically significant (P<0.001). Regarding the number of dissected lymph nodes, the median number in the GUA group was 3.0 (2.0–5.0), which was lower than that in the COT group [5.0 (3.0–8.0)], and the difference was statistically significant (P<0.001). In terms of total hospitalization cost, the GUA group had a median cost of 17,267.825 (15,491.05–18,491.37) CNY, which was significantly higher than that in the COT group [12,253.53 (12,010.09–12,638.52) CNY], and the difference was statistically significant (P<0.001). No statistically significant difference was observed in postoperative length of hospital stay between the two groups (P=0.47).

Figure 7 Operative time in the overweight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

Figure 8 Postoperative drainage volume in the overweight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

Figure 9 Number of dissected lymph nodes in the overweight group. COT, conventional open thyroidectomy; GUA, gasless transaxillary endoscopic thyroidectomy.

In addition, as shown in the overall comparison of perioperative outcomes (Table 2), a considerable proportion of patients were still found to have postoperative pathological stage pN1. Therefore, it was necessary to further analyze the factors associated with lymph node metastasis.

Postoperative complications across BMI strata

Postoperative complications were further compared between the GUA and COT groups in the normal-weight and overweight subgroups. Among normal-weight patients, there were no statistically significant differences between the GUA and COT groups in postoperative bleeding [2 (2.4%) vs. 4 (3.0%), χ²=0.056, P=0.81], lymphatic leakage [0 (0%) vs. 0 (0%)], transient hoarseness [5 (6.1%) vs. 7 (5.2%), χ²=0.074, P=0.79], incision infection [0 (0%) vs. 0 (0%)], or postoperative hypoparathyroidism [3 (3.7%) vs. 4 (3.0%), χ²=0.074, P=0.79] (Table 6).

Similarly, among overweight patients, no statistically significant differences were observed between the GUA and COT groups in postoperative bleeding [2 (3.6%) vs. 3 (2.4%), χ²=0.182, P=0.67], lymphatic leakage [0 (0%) vs. 0 (0%)], transient hoarseness [5 (8.9%) vs. 7 (5.7%), χ²=0.645, P=0.42], incision infection [1 (1.8%) vs. 3 (2.4%), χ²=0.075, P=0.78], or postoperative hypoparathyroidism [4 (7.1%) vs. 5 (4.1%), χ²=0.763, P=0.38] (Table 7).

These results indicated that the incidences of common postoperative complications were low in both surgical groups across BMI strata, and no significant difference in short-term postoperative complication profiles was observed between GUA and COT.

Cosmetic satisfaction across BMI strata

Cosmetic satisfaction was further evaluated in the normal-weight and overweight subgroups. Among normal-weight patients, 1 patient (1.2%) in the GUA group and 5 patients (3.7%) in the COT group reported dissatisfaction; 3 patients (3.7%) and 9 patients (6.7%) reported neutral satisfaction; 46 patients (56.1%) and 80 patients (59.7%) reported satisfaction; and 32 patients (39.0%) and 40 patients (29.9%) reported very high satisfaction, respectively. When satisfaction and very high satisfaction were combined, the overall cosmetic satisfaction rate was higher in the GUA group than in the COT group [78 (95.1%) vs. 120 (89.6%)], although the difference was not statistically significant (χ²=2.066, P=0.15) (Table 8).

Among overweight patients, 1 patient (1.8%) in the GUA group and 7 patients (5.7%) in the COT group reported dissatisfaction; 4 patients (7.1%) and 13 patients (10.6%) reported neutral satisfaction; 31 patients (55.4%) and 71 patients (57.7%) reported satisfaction; and 20 patients (35.7%) and 32 patients (26.0%) reported very high satisfaction, respectively. The overall cosmetic satisfaction rate was also higher in the GUA group than in the COT group [51 (91.1%) vs. 103 (83.7%)], but this difference did not reach statistical significance (χ²=1.721, P=0.19) (Table 9).

Although the differences were not statistically significant, cosmetic satisfaction tended to be higher in the GUA group than in the COT group in both BMI subgroups.

Relationship between tumor-related characteristics and pN stage

To further explore the factors associated with lymph node metastasis in PTC, this study analyzed the relationships of preoperative nodule size and BRAF mutation status with postoperative pathological lymph node stage (pN stage). The detailed results are shown in Tables 10,11.

With regard to nodule size, the median nodule diameter in the pN0 group was 5.3 (4.0–7.0) mm, which was significantly smaller than that in the pN1 group [7.0 (5.0–9.0) mm], and the difference was statistically significant (Z=4.328, P<0.001), suggesting that a larger nodule diameter was associated with a higher risk of lymph node metastasis.

With regard to BRAF mutation status, among BRAF-positive patients, 20 cases (60.6%) were classified as pN0 and 13 cases (39.4%) as pN1, whereas among BRAF-negative patients, 161 cases (64.7%) were classified as pN0 and 88 cases (35.3%) as pN1. No statistically significant difference in pN stage distribution was observed between the two groups (χ²=0.205, P=0.65), suggesting that BRAF mutation status was not significantly associated with lymph node metastasis.

Multivariable logistic regression analysis

To further identify independent factors associated with pN stage, BMI category, sex, age, and nodule size were included in a multivariable binary logistic regression model. Because the sample size in the underweight group was small and might affect the stability of the regression model, this group was excluded from the analysis. The results of the multivariable analysis are presented in Table 12. As shown in Table 12, sex [P=0.02, odds ratio (OR) =1.816, 95% confidence interval (CI): 1.107–2.979], age (P<0.001, OR =0.969, 95% CI: 0.951–0.987), and nodule size (P=0.004, OR =1.097, 95% CI: 1.031–1.169) were all independent factors associated with pN stage. Specifically, male sex, younger age, and larger nodule diameter were independently associated with a higher pN stage. In contrast, BMI category was not significantly associated with pN stage (P=0.47).

Correlation analysis

After identifying the independent factors associated with pN stage, this study further performed correlation analyses among the relevant variables.

Correlation analysis in the underweight group

Because the sample size of the underweight group was relatively small (n=16), which might affect the stability of the correlation analysis, this subgroup was not included in the subsequent analysis.

Correlation analysis in the normal-weight group

The results of correlation analyses among clinicopathological variables in the normal-weight group are presented in Table 13.

The analysis showed that, among general demographic characteristics, sex was positively correlated with BMI (r=0.221, P<0.01). Age was positively correlated with BMI (r=0.246, P<0.01), but negatively correlated with operative time (r=−0.206, P<0.01), postoperative drainage volume (r=-0.205, P<0.01), and pN stage (r=−0.179, P<0.01).

Regarding tumor-related characteristics, nodule size was positively correlated with pN stage (r=0.168, P<0.05) and negatively correlated with postoperative drainage volume (r=−0.193, P<0.01).

Among perioperative indicators, operative time was positively correlated with postoperative drainage volume (r=0.260, P<0.01) and total hospitalization cost (r=0.438, P<0.01). Postoperative drainage volume was positively correlated with postoperative length of hospital stay (r=0.409, P<0.01) and total hospitalization cost (r=0.557, P<0.01).

Correlation analysis in the overweight group

The results of correlation analyses among clinicopathological variables in the overweight group are shown in Table 14.

In terms of demographic factors, sex was positively correlated with nodule size (r=0.234, P<0.01) and pN stage (r=0.225, P<0.01). Age was negatively correlated with BMI (r=−0.183, P<0.05), operative time (r=−0.285, P<0.01), postoperative drainage volume (r=−0.251, P<0.01), and pN stage (r=−0.165, P<0.05). In addition, BMI was weakly positively correlated with nodule size (r=0.159, P<0.05).

With regard to tumor-related characteristics, nodule size was positively correlated with pN stage (r=0.186, P<0.05). pN stage was positively correlated with postoperative length of hospital stay (r=0.224, P<0.01).

Among perioperative indicators, operative time was positively correlated with postoperative drainage volume (r=0.329, P<0.01), postoperative length of hospital stay (r=0.210, P<0.01), and total hospitalization cost (r=0.506, P<0.01). Postoperative drainage volume was positively correlated with pN stage (r=0.166, P<0.05), postoperative length of hospital stay (r=0.725, P<0.01), and total hospitalization cost (r=0.431, P<0.01).

Discussion

Overview of the main findings

In the present study, we compared perioperative outcomes between GUA and COT in patients with PTC, and further explored the potential impact of BMI on surgical outcomes. The results showed that, compared with open surgery, endoscopic surgery was associated with longer operative time, greater postoperative drainage volume, and higher hospitalization costs. In addition, fewer lymph nodes were dissected in the endoscopic group; however, according to previous studies, this does not compromise the oncological efficacy of GUA. Although BMI showed statistically significant correlations with some perioperative indicators, the overall strength of these associations was weak. Notably, among overweight patients, BMI was positively correlated with nodule size, and preoperative nodule size was confirmed to be an independent predictor of lymph node metastasis. Furthermore, the incidences of common postoperative complications were low and comparable between the two surgical groups across BMI strata, while cosmetic satisfaction tended to be higher in the GUA group than in the COT group, although the differences were not statistically significant.

Comparison of perioperative outcomes between different surgical approaches

Overall, the findings of this study indicate that, across different BMI strata, endoscopic thyroidectomy differs from conventional open surgery in several perioperative aspects, mainly including operative time, postoperative drainage volume, number of dissected lymph nodes, and hospitalization cost. Specifically, in both the normal-weight and overweight groups, endoscopic surgery was associated with significantly longer operative time, which is consistent with previous reports (15,16,27). This may be attributable to the complexity of workspace creation, the longer operative pathway, and the increased difficulty of surgical exposure caused by thicker cervical adipose tissue. In addition, the learning curve for the endoscopic approach is relatively steep, and surgeon experience may also have an impact on operative time.

With regard to lymph node dissection, this study showed that in both normal-weight and overweight patients, the number of central compartment lymph nodes dissected was lower in the endoscopic group than in the open group (P<0.01), suggesting that the endoscopic approach may have certain limitations in the extent of central compartment dissection, which is consistent with some previous studies (15,16). However, a study from Korea reported that, in carefully selected patients with PTC, the two approaches were generally comparable in terms of surgical completeness-related indicators and 5-year recurrence outcomes (28). Regarding postoperative drainage volume, the present study demonstrated that the endoscopic group had significantly higher drainage volume than the open group across all BMI strata, which is also in line with previous domestic studies (16,27). A possible explanation is that endoscopic surgery requires the creation of a relatively large subcutaneous working space and involves a broader range of tissue dissection, thereby increasing postoperative exudation.

Postoperative complications and cosmetic satisfaction

In response to the clinical concerns regarding the safety of remote-access thyroid surgery, this study further compared common postoperative complications between GUA and COT across BMI strata. The results showed that the incidences of postoperative bleeding, lymphatic leakage, transient hoarseness, incision infection, and postoperative hypoparathyroidism were low in both surgical groups. No statistically significant differences were observed between GUA and COT in either the normal-weight or overweight subgroup. These findings suggest that, in carefully selected patients with low-risk PTC, GUA may achieve a short-term postoperative complication profile comparable to that of conventional open surgery.

This finding is clinically important because the transaxillary endoscopic approach requires a wider subcutaneous flap and a longer operative route than conventional open surgery. Theoretically, these technical characteristics may increase the risk of postoperative exudation, bleeding, infection, or traction-related symptoms. However, the present results did not show an increased incidence of common postoperative complications in the GUA group, suggesting that the procedure can be performed safely when the indications are appropriately selected and the operation is carried out by experienced surgeons.

Cosmetic satisfaction is one of the major reasons for choosing a remote-access endoscopic approach. In the present study, the overall cosmetic satisfaction rate was higher in the GUA group than in the COT group in both the normal-weight and overweight subgroups, although the differences did not reach statistical significance. This tendency is consistent with the theoretical advantage of GUA, as the transaxillary approach avoids a visible anterior neck scar and places the incision in a concealed axillary region. Therefore, even though GUA was associated with longer operative time, greater postoperative drainage volume, and higher hospitalization costs, it may provide potential cosmetic benefits for patients with high cosmetic expectations.

Nevertheless, these findings should be interpreted with caution. Cosmetic satisfaction in this study was assessed by telephone follow-up at 3 months after surgery using a simple 4-point satisfaction scale, rather than a validated patient-reported outcome measure or quality-of-life instrument. In addition, the retrospective design may have introduced recall bias and selection bias. Future prospective studies incorporating standardized scar assessment scales, validated cosmetic satisfaction instruments, and quality-of-life questionnaires are needed to further clarify the patient-centered benefits of GUA.

Relationship between BMI and perioperative indicators

The original aim of this study was to investigate the relationship between BMI and perioperative indicators. However, the results showed that although BMI was correlated to some extent with operative time, postoperative drainage volume, and the number of dissected lymph nodes, the overall strength of these correlations was weak. Notably, in clinical practice, some surgeons believe that in patients with a high BMI, the operative space during endoscopic surgery may be relatively easier to maintain, which could potentially improve procedural fluency. Subjectively, this may be reflected in better stability of the surgical field and smoother instrument handling. However, such a potential advantage was not reflected in the objective indicators evaluated in this study, such as operative time. In future studies, subjective surgeon-reported indicators, such as surgical difficulty scores or procedural fluency scores, could be incorporated to quantitatively evaluate the operative experience in high-BMI patients undergoing endoscopic surgery. This would allow a more comprehensive assessment of the impact of BMI from both subjective and objective perspectives. Previous studies have reported similar views and suggested that patients with a high BMI may have certain technical advantages during endoscopic surgery (29,30), although the available evidence remains controversial.

In addition, in other surgical fields, such as cardiac surgery and colorectal surgery, minimally invasive approaches have also shown certain advantages in obese patients (31-33). However, in the present study, no clear relationship was observed between increased BMI and improved perioperative outcomes, suggesting that this issue still requires further investigation.

Based on these findings, we believe that future studies could further refine the analysis of operative time by dividing the procedure into different stages. For example, open surgery could be subdivided into “incision-exposure-resection-hemostasis and closure”, whereas endoscopic surgery could be subdivided into “workspace creation-resection-hemostasis and closure”, in order to better clarify the specific impact of BMI on each surgical stage.

Nodule size and lymph node metastasis

With regard to oncological factors, this study showed that preoperative nodule size was significantly associated with pN stage and was confirmed as an independent risk factor in the multivariable analysis. The results indicated that for each 1-mm increase in nodule size, the risk of pN1 increased by approximately 9.7%. This finding is consistent with previous studies (34,35), suggesting that nodule size assessed by preoperative ultrasonography has important clinical predictive value.

In addition, this study found a positive correlation between BMI and nodule size in the overweight group, suggesting that increased body weight may be associated with larger tumor size. To some extent, this finding supports the hypothesis of a potential link between obesity and tumor progression.

Sex differences and potential mechanisms

In the stratified correlation analyses, different BMI groups showed distinct patterns.

In the overweight group, male sex was associated with larger tumors and a higher pN stage, which is consistent with previous studies (36-38). However, some basic studies have suggested that the androgen receptor (AR) may exert a suppressive effect on tumor progression (39-41), which appears to differ somewhat from the findings of the present study. Several possible explanations may account for this discrepancy. On the one hand, AR expression may be reduced in PTC, thereby weakening its tumor-suppressive effect (41). On the other hand, obesity-related chronic inflammation may play a key role in this process. Adipose tissue can secrete a variety of inflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), thereby creating a pro-tumor microenvironment (42). In addition, visceral fat is more prominently distributed in men and is more metabolically active, which may result in the release of a greater amount of pro-inflammatory factors and thus promote tumor progression (23-25). Meanwhile, obesity may also facilitate tumor initiation and progression through mechanisms such as immune suppression and insulin resistance (26,43-45).

Perioperative recovery and clinical significance

With regard to perioperative indicators, this study found that in the overweight group, postoperative drainage volume was more strongly correlated with postoperative length of hospital stay, suggesting that obesity may increase the burden of postoperative recovery and healthcare resource utilization. This finding is also consistent with previous studies in other surgical fields (46-48). Given that all patients included in this study had low-risk PTC and underwent relatively limited surgical resection, older patients were more likely to receive more conservative surgical strategies with less intraoperative trauma, which may partly explain this result. Unlike previous studies involving more extensive surgical trauma (49), the present study had greater consistency in both surgical procedures and patient selection, and therefore this finding appears reasonably plausible.

Clinical implications

Taken together, the present study suggests that in clinical practice, factors such as BMI, age, and tumor characteristics should be comprehensively considered to achieve individualized selection of surgical approaches. In addition to tumor-related and perioperative factors, postoperative complication risk and cosmetic expectations should also be considered during preoperative counseling. For patients who meet the indications for endoscopic surgery and have strong concerns regarding anterior neck scarring, GUA may be considered as an alternative approach after full discussion of its potential advantages and disadvantages. For overweight patients, greater attention should be paid to perioperative management strategies in order to optimize surgical safety and the efficiency of healthcare resource utilization. At the same time, preoperative nodule size, as an important predictor of lymph node metastasis, should be given full consideration in clinical decision-making.

Conclusions

This study showed that across different BMI categories, endoscopic thyroidectomy was associated with longer operative time, greater postoperative drainage volume, and higher medical costs than open surgery during the perioperative period, and these differences were particularly evident in overweight patients. In addition, the endoscopic approach appeared to have certain limitations in the number of lymph nodes dissected. However, the incidences of common postoperative complications were low and comparable between the GUA and COT groups across BMI strata, suggesting that GUA may achieve a similar short-term safety profile in carefully selected patients. In addition, cosmetic satisfaction tended to be higher in the GUA group, although the differences did not reach statistical significance. Although BMI was only weakly correlated with most perioperative indicators, a stronger positive correlation between postoperative drainage volume and length of hospital stay was observed in overweight patients, suggesting that increased body weight may be associated with prolonged postoperative recovery and greater resource utilization. The study also found that nodule size measured by preoperative ultrasonography was strongly associated with postoperative pN stage and served as an independent predictor, indicating its important value in clinical assessment.

Furthermore, this study found that overweight male patients were more likely to present with larger lesions and lymph node metastasis, which may be related to the combined effects of obesity-associated chronic inflammation, immune suppression, and metabolic abnormalities in promoting tumor progression. Given the differences in surgical risk and postoperative recovery among patients with different BMI categories, we recommend that BMI and age should be fully incorporated into preoperative evaluation to facilitate individualized selection of surgical approach. Overall, BMI, tumor characteristics, postoperative safety, cosmetic expectations, and medical cost should be comprehensively considered when selecting the appropriate surgical approach for patients with low-risk PTC.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0209/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0209/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0209/prf

Funding: The work was supported by grants from the Project of Huzhou Basic Public Benefit Research (No. 2022GZB09, to G.Y.).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-0209/coif). G.Y. reports grants from the Project of Huzhou Basic Public Benefit Research. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Huzhou Central Hospital (approval No. 202506022-01), and the requirement for informed consent was waived due to the retrospective nature of the study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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