Hemithyroidectomy versus total thyroidectomy for patients with differentiated thyroid cancer: a systematic review and meta-analysis

Introduction

The incidence of thyroid cancer has risen dramatically in recent decades, which has been largely attributed to advancements in diagnostic techniques that enable detection of smaller tumors (1,2). Some controversy persists regarding the optimal surgical treatment for patients with low-risk differentiated thyroid cancer (DTC), since both hemithyroidectomy and total thyroidectomy have distinct advantages and disadvantages (3-5). Total thyroidectomy removes the entire thyroid gland, which enhances the protective effects of radioactive iodine (RAI) therapy, and it allows for improved postoperative monitoring to inform risk assessment and subsequent treatment decisions (6-8). Furthermore, total thyroidectomy facilitates accurate postoperative monitoring using highly sensitive thyroglobulin assays, which are essential for reliable detection of recurrence and effective long-term follow-up (9). Conversely, hemithyroidectomy offers lower risks of certain surgical complications, shorter hospital stays, reduced surgical costs, and the possibility of decreasing the need for lifelong medical treatment for persistent hypothyroidism (10-19). In 2015, the revised American Thyroid Association (ATA) guidelines recommended either hemithyroidectomy or total thyroidectomy as acceptable primary treatments for patients with thyroid cancer between 1 cm and 4 cm without extrathyroidal extension and without clinical evidence of lymph node metastases (7). Moreover, the updated guidelines suggest that thyroid lobectomy alone may be a sufficient initial treatment for low-risk papillary and follicular carcinomas (7). The 2025 ATA guidelines reaffirm these recommendations, stating that hemithyroidectomy remains the preferred initial surgical treatment for patients with low-risk, unilateral DTC measuring >2 and ≤4 cm, owing to its lower complication risk (20).

Following the release of the 2015 ATA guidelines, several studies observed a significant increase in hemithyroidectomy utilization among patients with DTC ≥1 cm (21-24). A study conducted using the National Cancer Database (NCDB) supports these findings, while also revealing some systematic shifts toward hemithyroidectomy prior to the 2015 ATA guidelines (25). Nonetheless, total thyroidectomy remained the mainstay surgical treatment for patients with DTC between 1 and 4 cm, and hemithyroidectomy utilization did not exceed 25% in the NCDB (25). The relatively low utilization suggests that clinicians and/or patients appear to be signaling some concern about the use of hemithyroidectomy.

To better understand the development of the evidence base that prompted the shift towards hemithyroidectomy and the revision to the ATA guidelines, and to investigate the pooled effects of surgical outcomes associated with both hemithyroidectomy and total thyroidectomy, we conducted a systematic literature review and meta-analyses. The primary objectives of this study are to trace the accumulation of evidence supporting hemithyroidectomy prior to the release of the 2015 ATA guidelines and to synthesize the available data on surgical outcomes for both procedures. We present this article in accordance with the MOOSE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-364/rc).

Methods

Systematic literature review

Since this review aimed to gather evidence published after the 2009 ATA guidelines were released, we performed a search of MEDLINE (PubMed) for relevant studies published between 1 January 2009 and 31 May 2022. Studies were limited to English language reports, and search terms included: “thyroidectomy”, “hemithyroidectomy”, “lobectomy”, “thyroid carcinoma”, “thyroid neoplasms”, and “low risk thyroid carcinoma”. The literature search and data extraction were independently conducted by two authors, both of whom have prior experience in conducting systematic reviews and meta-analyses. All selected references were imported into Covidence software, which is web-based software for managing and streamlining systematic reviews (26). Duplicate studies were automatically removed, and we screened titles and abstracts to determine which studies warranted a full-text review in the Covidence platform. Additionally, we reviewed the bibliographies of review articles to uncover any potentially relevant studies that may not have appeared in our electronic database search results. No contact with study authors was made, as all required data were available from the published reports.

Selection criteria

Studies were eligible for inclusion in our analysis if they met the following criteria: the study cohort consisted of adults (age 18 years and older) with DTC ≥1 cm; hemithyroidectomy and total thyroidectomy were compared as two distinct surgical treatments; and patient outcomes, such as recurrence rates, overall survival (OS), disease-free survival (DFS), and/or disease-specific survival (DSS), were reported. We placed no restrictions on study design, incorporating both randomized controlled trials and observational cohort studies.

Studies were excluded from our analysis if they involved children or adolescents (under 18 years of age), included patients with thyroid microcarcinoma without providing a separate subgroup analysis for patients with DTC tumors ≥1 cm, did not report at least one outcome of interest, or contained data that were not extractable (e.g., outcomes were only reported in graphical format without detailed data, or essential information was missing).

Data extraction

Data were extracted from all eligible studies using a standardized data extraction form, collecting information on the first author, year of publication, country, study design, database, study period, number of patients (separately for hemithyroidectomy and total thyroidectomy), participant characteristics, surgical outcomes, and duration of follow-up. Surgical outcomes included data to calculate the risk ratio (RR) or hazard ratio (HR) of the four outcomes of interest, as well as variance measures or 95% confidence intervals (CIs).

Quality assessment

The methodological quality of the studies included was assessed using the Newcastle-Ottawa Scale criteria (27). This scoring system evaluates the quality of cohort studies in three domains: selection, comparability, and outcomes (27). The selection domain considers the representativeness of the exposed cohort, the selection of the non-exposed cohort, ascertainment of exposure, and demonstration of absence of outcome at the beginning of studies. Comparability assesses the degree to which cohorts are comparable, based on the study design or analysis. Outcome evaluates the adequacy of the outcome assessment, whether the follow-up duration was sufficient for outcomes to occur, and the adequacy of cohort follow-up. Each study could earn one point for each criterion within the selection and outcome domains, and up to two points for comparability, allowing for a maximum possible score of nine. Studies scoring six or more out of nine total points were deemed high quality (27).

Statistical analysis

We first conducted conventional meta-analyses to compare recurrence rates, DFS, OS, and DSS of hemithyroidectomy and total thyroidectomy among patients with DTC ≥1 cm. We tested for heterogeneity across eligible studies using a Woolf test, with P<0.05 indicating significant heterogeneity (28). If the included studies showed no significant heterogeneity, we applied a fixed-effects meta-analysis model, which was the Mantel-Haenszel method for RR and the inverse variance method for HR (29,30). Otherwise, if the studies showed significant heterogeneity, we used a random-effects meta-analysis model, including the DerSimonian-Laird method for pooling RRs, and the inverse variance method for pooling HRs (31). We further conducted cumulative meta-analyses to show how the overall pooled estimates changed as each study was added incrementally in the year of publication. Subgroup analyses for HR of recurrence rates, DFS, and OS were also conducted. Publication bias was assessed using Begg’s rank correlation test (P<0.10) and visually examined using funnel plots (32). All statistical analyses were performed using R software (version 4.1.2: https://www.r-project.org) with the rmeta package (33).

Results

Literature search results

The initial search in PubMed returned 567 potentially relevant studies, and 11 additional records were identified from the bibliographies of review articles (Figure 1). Upon reviewing the titles, 507 studies were excluded because of incompatible research questions. After assessing 60 abstracts and applying exclusion criteria, 11 articles were eliminated as they reported unrelated results. Full text reviews were performed for the remaining 49 articles, and 35 studies were excluded based on predefined exclusion criteria. Among these excluded studies, 18 reported irrelevant outcomes, 12 involved patients with tumor size less than 1 cm without providing subgroup analysis for tumor larger than 1 cm, three contained non-extractable data, one had ambiguous tumor size, and one study was excluded for other reasons. The final sample of our systematic review consisted of 14 studies (34-47). Figure 1 shows the PRISMA flow chart reporting details of the study selection process and the corresponding exclusion criteria.

Figure 1 PRISMA diagram for the systematic literature review.

The characteristics of the included studies are summarized in Table 1. The 14 studies were published between 2009 and 2020. All studies were observational cohort studies; no randomized controlled trials comparing hemithyroidectomy to total thyroidectomy were identified. Three of the 14 studies were conducted using a national database, and two of them specifically used the NCDB. One study used both NCDB and the Surveillance, Epidemiology, and End Results (SEER) database; however, only data from the SEER database were included to avoid potential selection bias. The remaining 11 studies utilized data from single institutions. In accordance with the inclusion criteria, only data for tumors ≥1 cm were extracted from the studies by Vaisman et al., Nixon et al., Lim et al., and Ji et al. The included studies comprised a total of 176,238 patients, with 88.4% (n=155,803) having undergone total thyroidectomy, and only 11.6% (n=20,435) receiving hemithyroidectomy. The mean follow-up time was 8 years.

Publication bias assessment

Publication bias was examined by funnel plots. As seen in Figure 2, the included studies appeared to show minimal publication bias, though for some outcomes the number of studies was small.

Figure 2 Funnel plot for publication bias. (A) Funnel plot for publication bias for recurrence rates, HR of recurrence rates, DFS, and HR of DFS. (B) Funnel plot for publication bias for OS, HR of OS, and DSS. DFS, disease-free survival; DSS, disease-specific survival; HR, hazard ratio; HT, hemithyroidectomy; OS, overall survival; TT, total thyroidectomy.

Meta-analyses of recurrence

The meta-analysis of recurrence encompassed 11 studies, totaling 8,841 patients with a median follow-up of 70 months. The majority of studies reported no significant differences between hemithyroidectomy and total thyroidectomy in terms of recurrence rate, with two exceptions. Hassanain et al. found that hemithyroidectomy had a significantly lower rate of recurrence compared to total thyroidectomy, and Choi et al. reported the opposite result. Overall, the pooled recurrence rates were 7.7% for the hemithyroidectomy group and 5.8% for the total thyroidectomy group. Because of the significant heterogeneity, a random-effects model using DerSimonian-Laird method was applied. Figure 3A shows the results of the conventional meta-analysis of recurrence rates, revealing no significant differences between hemithyroidectomy and total thyroidectomy (RR: 1.036, 95% CI: 0.698–1.538). Figure 3B presents the results of the cumulative meta-analysis of recurrence rates. Starting from Hassanain et al. in 2010, the RR for recurrence favored hemithyroidectomy. After the publication of Vaisman et al., the RR for recurrence became insignificant and remained so with each subsequent study.

Figure 3 Recurrence rate and HR of recurrence rate among patients with DTC ≥1 cm underwent HT vs. TT. (A) Random effects (DerSimonian-Laird) meta-analysis of recurrence rates among patients with DTC ≥1 cm underwent HT vs. TT. (B) Cumulative meta-analysis of recurrence rates among patients with DTC ≥1 cm underwent HT vs. TT. (C) Random effects (inverse variance) meta-analysis of HR for recurrence rates among patients with DTC ≥1 cm underwent HT vs. TT. (D) Cumulative meta-analysis of HR for recurrence rates among patients with DTC ≥1 cm underwent HT vs. TT. CI, confidence interval; DTC, differentiated thyroid cancer; HR, hazard ratio; HT, hemithyroidectomy; RR, risk ratio; TT, total thyroidectomy.

Meta-analyses of HR for recurrence

A subgroup analysis of the HR for recurrence included three studies, comprising 3,585 patients. Kim et al. demonstrated a significantly higher HR for recurrence in patients receiving hemithyroidectomy compared to those undergoing total thyroidectomy. The other two studies revealed similar HRs for recurrence between the two surgical treatments. Due to the significant heterogeneity, a random-effects model using the inverse variance method was applied, and the results of the conventional meta-analysis of HR for recurrence are presented in Figure 3C. We observed no significant differences between hemithyroidectomy and total thyroidectomy in terms of recurrence rates, with a pooled rate of HR for recurrence rates of 1.463 (95% CI: 0.526–4.070). As illustrated in Figure 3D, the cumulative meta-analysis shows that TT was favorable in Kim et al.’s study, and then HR became insignificant as more studies were pooled incrementally.

Meta-analyses of DFS

The meta-analysis of DFS included 6,851 patients from four studies. DFS rates were 90.1% in the hemithyroidectomy group and 93.7% in the total thyroidectomy group. All four studies reported no significant differences between hemithyroidectomy and total thyroidectomy. Since this meta-analysis of DFS had no significant heterogeneity, we applied a fixed-effects model using the Mantel-Haenszel method. Figure 4A shows the results of the conventional meta-analysis of DFS. We found that total thyroidectomy provided better DFS compared to hemithyroidectomy, with a pooled estimated RR of 0.980 (95% CI: 0.963–0.997). Digging deeper, the cumulative meta-analysis of DFS showed that Choi et al.’s study drove the outcome to favor total thyroidectomy (Figure 4B).

Figure 4 DFS and HR of DFS among patients with DTC ≥1 cm underwent HT vs. TT. (A) Fixed effects (Mantel-Haenszel) meta-analysis of DFS among patients with DTC ≥1 cm underwent HT vs. TT. (B) Cumulative meta-analysis of DFS among patients with DTC ≥1 cm underwent HT vs. TT. (C) Fixed effects (inverse variance) meta-analysis of HR for DFS among patients with DTC ≥1 cm underwent HT vs. TT. (D) Cumulative meta-analysis of HR for DFS among patients with DTC ≥1 cm underwent HT vs. TT. CI, confidence interval; DFS, disease-free survival; DTC, differentiated thyroid cancer; HR, hazard ratio; HT, hemithyroidectomy; RR, risk ratio; TT, total thyroidectomy.

Meta-analyses of HR for DFS

A subgroup analysis of the HR for DFS included 1,240 patients, of whom 34.9% received hemithyroidectomy. All three studies reported no significant differences in HR for DFS. Due to the absence of significant heterogeneity in the meta-analysis of HR for DFS, a fixed-effects model using the inverse variance method was employed. As seen in Figure 4C, the fixed-effect pooled HR of DFS was 0.939 (95% CI: 0.610–1.447), suggesting no significant difference in HR of DFS between hemithyroidectomy and total thyroidectomy. Figure 4D presents the cumulative meta-analysis of HR for DFS, demonstrating that the HR for DFS remained consistently insignificant with each subsequent publication.

Meta-analyses of OS

The meta-analysis of OS included 76,029 patients in six studies. The OS rates were 92.9% in the hemithyroidectomy group and 94% in the total thyroidectomy group. Except for Adam et al.’s 2014 study, which found that patients receiving hemithyroidectomy had longer OS than those receiving total thyroidectomy, all studies demonstrated no significant difference in OS between the two surgical treatments. Due to significant heterogeneity in OS across studies, a random-effects model using the DerSimonian-Laird method was applied. As seen in Figure 5A, hemithyroidectomy and total thyroidectomy showed similar OS rates with a RR of 0.995 (95% CI: 0.985–1.006). Figure 5B shows the results of the cumulative meta-analysis of OS; the pooled random-effects RRs were consistently insignificant as each study was published incrementally.

Figure 5 OS and HR of OS among patients with DTC ≥1 cm underwent HT vs. TT. (A) Random effects (DerSimonian-Laird) meta-analysis of OS among patients with DTC ≥1 cm underwent HT vs. TT. (B) Cumulative meta-analysis of OS among patients with DTC ≥1 cm underwent HT vs. TT. (C) Fixed effects (inverse variance) meta-analysis of HR for OS among patients with DTC ≥1 cm underwent HT vs. TT. (D) Cumulative meta-analysis of HR for OS among patients with DTC ≥1 cm underwent HT vs. TT. CI, confidence interval; DTC, differentiated thyroid cancer; HR, hazard ratio; HT, hemithyroidectomy; OS, overall survival; RR, risk ratio; TT, total thyroidectomy.

Meta-analyses of HR for OS

The meta-analysis of HR of OS included 89,726 patients from three studies, with 9.4% of patients in these studies receiving hemithyroidectomy. All three studies reported no significant differences in HR of OS between hemithyroidectomy and total thyroidectomy. As there was no significant heterogeneity in the meta-analysis of HR of OS, a fixed effects model using the inverse variance method was applied. Figure 5C shows that the pooled HR was 0.941 (95% CI: 0.839–1.005). In addition, as seen in Figure 5D, the cumulative meta-analysis shows that the pooled fixed-effects RRs were consistently insignificant as more studies were published over time.

Meta-analyses of DSS

The meta-analysis of DSS included 6,233 patients from two studies. The DSS rates were 99.6% in the hemithyroidectomy group and 99.8% in the total thyroidectomy group. While Ebina et al. reported no significant difference between hemithyroidectomy and total thyroidectomy, Choi et al. found that hemithyroidectomy had a significantly longer DSS than total thyroidectomy. Due to the absence of significant heterogeneity between these studies, a fixed-effects model using the Mantel-Haenszel method was used to pool the RRs. As seen in Figure 6A, the fixed-effects pooled RR was 1.001 (95% CI: 0.998–1.005), indicating no significant difference in DSS rates between the two surgical modalities. Given that only two studies reported DSS rates, results of the cumulative meta-analysis appear the same as those of the conventional meta-analysis (Figure 6B).

Figure 6 DSS among patients with DTC ≥1 cm underwent HT vs. TT. (A) Fixed effects model (Mantel-Haenszel) meta-analysis of DSS among patients with DTC ≥ 1 cm underwent HT vs. TT. (B) Cumulative meta-analysis of DSS among patients with DTC ≥ 1 cm underwent HT vs. TT. CI, confidence interval; DSS, disease-specific survival; DTC, differentiated thyroid cancer; HT, hemithyroidectomy; RR, risk ratio; TT, total thyroidectomy.

Quality assessment

The methodological quality of the 14 studies included into this meta-analysis was evaluated using the Newcastle-Ottawa Scale. With a maximum possible score of 9, the mean total score for the studies was 8.3 (range, 7–9). This score indicates that the overall methodological quality was good for the studies included in our analysis (Table 2). The 14 studies generally received good scores for selection criteria, comparability, and outcome criteria.

Discussion

This meta-analysis examined 14 retrospective cohort studies published between 2009 and 2022 that investigated surgical outcomes following hemithyroidectomy and total thyroidectomy among patients with DTC ≥1 cm. Our findings showed that total thyroidectomy was associated with slightly better DFS compared to hemithyroidectomy. Aside from this, our analyses did not observe statistically significant differences in recurrence, OS, and DSS between the two procedures. Despite this, it is noteworthy that the point estimates for recurrence, DFS, and OS were more favorable following total thyroidectomy. Furthermore, our pooled analyses indicate that more robust evidence has emerged since 2014, which may have encouraged surgeons to start considering hemithyroidectomy as a safe procedure for treatment of patients with DTC ≥1 cm.

Considering the relatively small sample size and low event rate for some outcomes, results from this study—particularly the finding that recurrence rates for lobectomy were not significantly greater than recurrence rates for total thyroidectomy—should be interpreted with caution. Several published systematic reviews and meta-analyses have evaluated clinical outcomes following hemithyroidectomy and total thyroidectomy among patients with low-risk DTC. Many of these studies reported similar recurrence rates between the two procedures (48,49). For instance, one study analyzed ten eligible articles and concluded that both procedures can achieve low recurrence rates and high survival in patients with low-risk DTC (49). Another meta-analysis of 16 studies by Bojoga et al. demonstrated that both hemithyroidectomy and total thyroidectomy have low recurrence rates and no significant differences in OS, DFS, and DSS (48). However, assessments of surgical outcomes varied among studies. Zhang et al. reported that hemithyroidectomy increased the risk of recurrence in patients with papillary thyroid cancer >1 cm and was associated with higher mortality in patients with papillary thyroid cancer 2–4 cm (50). Despite the 2015 ATA guidelines recommending hemithyroidectomy as an acceptable treatment option for selected patients, the use of less aggressive treatment remains debated. Our study involved patients with DTC ≥1 cm only and synthesized the available data on surgical outcomes for both procedures. Unlike previous research, our analysis traced the accumulation of evidence supporting hemithyroidectomy prior to the release of the 2015 ATA guidelines. This study highlights the evolution of the evidence base that prompted the shift towards hemithyroidectomy and the revision to the ATA guideline.

In the decision-making process for treating patients with DTC, both hemithyroidectomy and total thyroidectomy present distinct advantages. Total thyroidectomy simplifies the administration of RAI therapy since it removes the entire thyroid gland, which eliminates any remaining normal thyroid tissue that could interfere with RAI therapy (7,8). RAI therapy helps to ablate residual thyroid tissue and treat occult foci of cancer (7,8). Furthermore, total thyroidectomy enables more accurate postoperative thyroglobulin surveillance, which is crucial for risk stratification and guiding subsequent treatment decisions (6,7). In contrast, hemithyroidectomy has several benefits over total thyroidectomy, including lower risks of surgical complications such as hematoma, hypothyroidism, hypoparathyroidism, and recurrent laryngeal nerve (RLN) injury (13-16). Hemithyroidectomy is also associated with shorter hospital stays and lower surgical costs (10-12). Additionally, retaining some natural thyroid function after hemithyroidectomy can reduce the need for lifelong treatment for hypothyroidism (17-19). In selecting a surgical approach for smaller thyroid tumors, patients face a trade-off between less uncertainty about recurrence and higher quality of life due to having some residual thyroid function. Surgeons will be challenged in helping patients navigate these trade-offs.

Although the hemithyroidectomy utilization has increased in recent years, total thyroidectomy remains the predominant treatment for patients with DTC between 1 cm and 4 cm, with over 75% of cases (25). This preference for total thyroidectomy in clinical practice is likely due to concerns regarding surgical outcomes following hemithyroidectomy. The 2009 ATA guidelines recommended near-total or total thyroidectomy for DTC >1 cm (51). This recommendation was based on several studies, including a retrospective study by Bilimoria et al., which examined the surgical outcomes of hemithyroidectomy and total thyroidectomy in a cohort of 52,173 patients with papillary thyroid cancer from the NCDB (51,52). Their findings suggested that total thyroidectomy led to lower recurrence rates and improved survival for patients with papillary thyroid cancer ≥1 cm, compared to lobectomy (52). However, critics pointed out that the study did not account for important confounders such as comorbidities, multifocality, extrathyroidal extension, and completeness of resection (38,51,53,54). They also highlighted that the outcome variable—recurrence—has substantial missing values (38,51,53,54). A later study examining the same research question in a cohort of 22,724 patients with papillary thyroid cancer from the SEER database found no significant difference in surgical outcomes between the two procedures (55). More recently, Stevens et al. [2023] reassessed the survival outcomes associated with lobectomy versus total thyroidectomy using a large NCDB cohort of over 84,000 patients and applied rigorous analytic techniques, including flexible parametric survival models, inverse probability of treatment weighting, and two-stage least squares regression to adjust for both observed and unmeasured confounders. Their findings showed no significant difference in 5- or 10-year OS across all subgroups, including tumor size, age, and mortality risk (56). These conflicting findings perpetuate the debate regarding the optimal surgical approach.

Our research analyzed studies published since 2009 that investigated surgical outcomes following hemithyroidectomy and total thyroidectomy. Most studies selected for this meta-analysis indicated that hemithyroidectomy was not associated with inferior surgical outcomes in properly selected low-risk patients. Hassanain et al. was the only study that reported a significantly higher recurrence rate with total thyroidectomy, but their findings may have been influenced by selection bias (34). In their study, disease stage was described using the American Joint Committee on Cancer (AJCC) tumor, nodes, metastasis (TNM) system (34,57). Out of 126 patients who received hemithyroidectomy, 19 patients (15%) were classified with a high TNM stage, while 107 patients (85%) had a low TNM stage. There were four recurrences (3.2%) among hemithyroidectomy patients; two of these were in patients with a low TNM stage (1.9%), and two were in patients with a high TNM stage (10.5%). In contrast, 54 patients underwent a total thyroidectomy, with 28 patients (51.9%) having a low TNM stage and 26 patients (48.1%) classified as a high TNM stage. Among these patients, there were 12 patients (22.2%) that had recurrences, including four patients (14.3%) with low a TNM stage and eight patients (30.8%) with a high TNM stage. In their study, patients with higher risk features were more likely to experience recurrence than those with lower risk features for both procedures. Moreover, the total thyroidectomy group contained more than three times the rate of patients with a high TNM stage than the hemithyroidectomy group (48.1% vs. 15%). Instead of concluding that total thyroidectomy was associated with a higher recurrence rate than hemithyroidectomy, this selection bias might be contributing to the higher recurrence rate reported in the total thyroidectomy group compared to the hemithyroidectomy group observed in Hassanain et al. In 2014, Adam and colleagues conducted a Cox proportional-hazards model using data form the NCDB and found no significant survival advantage for total thyroidectomy over lobectomy in 61,775 patients with papillary thyroid cancer 1–4 cm (38). Subsequently, the 2015 ATA guidelines recommended hemithyroidectomy as an acceptable surgical option for properly selected low-risk patients. Choi and colleagues analyzed data of 5,266 patients with DTC 1–4 cm in a hospital and found that total thyroidectomy reduced recurrence (43). However, they noted that for tumors with low-risk features, such as being unifocal, intrathyroidal, and lymph node metastasis-negative, hemithyroidectomy provided similar surgical outcomes (43). Notably, Kim et al. found that hemithyroidectomy was associated with significantly higher risk of recurrence for patients with contralateral nodules compared to total thyroidectomy (41). The study by Xu et al. reported a slightly higher recurrence rate in cases of total thyroidectomy compared to hemithyroidectomy, although this difference was not statistically significant (46). It is possible that this increase in recurrence following total thyroidectomy may largely be attributable to selection bias. It was observed that individuals who underwent total thyroidectomy were more likely to have multifocality (45.0% vs. 12.6%), extrathyroidal extension (33.2% vs. 22.4%), and lymph node metastasis (56.0% vs. 42.3%) compared to those who underwent hemithyroidectomy. Although the association between multifocality and recurrence rate remains controversial, both extrathyroidal extension and lymph node metastasis have been identified as two risk features for recurrence in low-risk DTC (7,58,59).

Selecting the appropriate initial treatment relies on precise preoperative risk stratification, which considers not only tumor size but also various other factors that may also influence the decision. For instance, patients with a history of neck irradiation and/or a familial history of DTC may be better served by total thyroidectomy as the initial surgical intervention (7,60,61). Moreover, certain high-risk features necessitating completion thyroidectomy can only be identified after final histology, such as aggressive variants of DTC, extracapsular invasion, and vascular invasion (7,60-62). Additionally, staying up-to-date with latest research and having access to the latest technology are crucial, since molecular and genetic studies are not universally available (61). Other factors, such as surgeon and patient preferences, as well as the quality of communication between patient and surgeon, may also affect the treatment decision (63,64). A recent systematic review and meta-analysis reported that nearly one-third of patients develop hypothyroidism after hemithyroidectomy, highlighting the importance of considering individual risk factors when planning the extent of surgery (4).

This study has serval limitations. First, the lack of randomized retrospective studies led us to base our estimates on non-randomized retrospective studies, which are susceptible to selection bias and heterogeneity. However, the included studies are all recently published population-based research, reflecting a current understanding of procedure selection. Second, different patient selection criteria across studies may result in selection bias. Some studies incorporated patients with extrathyroidal extension and/or lymph node metastases, which could affect the outcomes after procedures. Third, disparate follow-up durations and inadequate records of adverse events may lead to bias. Fourth, detailed data on recurrence patterns (e.g., local, contralateral lobe, paratracheal, or distant dissemination), surgical techniques such as paratracheal dissection, and extended follow-up durations were not consistently reported across the included studies, which limited our ability to perform subgroup analyses addressing these factors. Finally, only studies published in English were included in the present study, which may lead to publication bias. However, the main goals of this study were to trace the accumulation of evidence supporting hemithyroidectomy prior to the release of the 2015 ATA guidelines and to investigate the pooled effects of surgical outcomes associated with hemithyroidectomy and total thyroidectomy, which necessitated the inclusion of studies using populations in the U.S. and provided justification for the exclusion criterion.

Conclusions

In this systematic review and meta-analysis, we found that total thyroidectomy was associated with slightly greater DFS relative to hemithyroidectomy, but no statistically significant differences were observed in recurrence, OS, and DSS between the two procedures. Notably, the point estimates for recurrence, DFS, and OS favored total thyroidectomy. Moreover, the accumulation of evidence supporting hemithyroidectomy may have prompted the ATA to revise their guidelines and encouraged surgeons to increasingly consider hemithyroidectomy as a safe procedure for treating patients with DTC ≥1 cm. The emergence of more robust evidence since 2014 was more likely to be the catalyst for the shift towards hemithyroidectomy prior to the release of the 2015 ATA guidelines for some hospitals. Our findings contribute to a better understanding of surgical outcomes associated with hemithyroidectomy and total thyroidectomy for patients with DTC ≥1 cm and provide valuable data for patient counseling during the treatment decision-making process. Future research that utilizes randomized controlled trials and larger patient cohorts, including data on long-term follow-up, is needed to thoroughly examine both procedures.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the MOOSE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-364/rc

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-364/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-364/coif). C.S. reports receiving grants from NIH, DoD, and PCORI. 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.

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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