Modern management of phyllodes tumours: closing the gap between evidence and practice

The recent publication of the UK Association of Breast Surgery (ABS) guidelines for the contemporary management of phyllodes tumours (PT) represents a significant milestone in addressing one of breast surgery’s most challenging diagnostic and therapeutic dilemmas (1). These comprehensive recommendations, developed through rigorous multidisciplinary collaboration, offer much-needed clarity in managing these rare but complex lesions that have historically been subject to considerable practice variation and overtreatment.

PTs present a unique clinical challenge, accounting for only 0.5% of all breast tumours yet demanding sophisticated management decisions. With approximately 60 new cases of malignant PTs diagnosed annually in England, the rarity of these lesions contributes to the wide variation in clinical practice observed both within the UK and internationally (2). This scarcity of experience has led to a concerning tendency toward overtreatment, particularly of benign lesions in non-specialist centres (3). The biphasic nature of PTs, comprising both stromal and epithelial components, creates diagnostic challenges that extend from initial core biopsy through to final histopathological classification. The distinction between cellular fibroadenoma and PT, and subsequently between benign, borderline, and malignant subtypes, requires considerable pathological expertise. This diagnostic complexity is reflected in the guidelines’ emphasis on multidisciplinary team review and the recommendation for expert pathology review in difficult cases (1).

Perhaps the most significant contribution of these guidelines lies in their evidence-based approach to surgical margins, an area that has been plagued by uncertainty and varied practice. The comprehensive literature review encompassing over 3,000 patients across multiple studies provides the foundation for nuanced margin recommendations that move away from the historical “one-size-fits-all” 10 mm margin approach (1). For benign PTs, the guidelines advocate for complete excision with intact capsule, acknowledging that most recurrences occur with involved margins but recognizing that re-excision of positive margins may have uncertain benefit given the generally low recurrence rates (11% overall) (4). This balanced approach reflects the benign nature of these lesions while maintaining appropriate oncological principles.

The recommendations become more stringent for borderline tumours, with a target 5 mm margin and re-excision recommended for margins less than 3 mm. This graduated approach acknowledges the intermediate risk profile of borderline lesions and the reported 26% rate of histological upgrade to malignant subtype at recurrence (5). For malignant PTs, the 10 mm target margin with re-excision recommended for margins less than 5 mm reflects the aggressive potential of these lesions and the documented association between inadequate margins and local recurrence (5,6). Importantly, immediate breast reconstruction is considered safe and may help optimize cosmetic outcomes in selected cases (1).

The guidelines also strongly endorse breast-conserving surgery when adequate margins can be achieved, representing an important paradigm shift. The evidence demonstrates no difference in distant disease-free survival or overall survival between breast-conserving surgery and mastectomy, providing reassurance that organ preservation does not compromise oncological outcomes. This recommendation has particular significance given the younger age demographic typically affected by PTs, where breast conservation can have profound implications for body image and quality of life. The recognition that complex oncoplastic techniques may be required to achieve adequate margins while preserving breast volume highlights the importance of surgical expertise in managing these cases, while discussion at oncoplastic multidisciplinary team meetings ensures that patients benefit from the full spectrum of reconstructive options available.

One of the clearest messages from these guidelines concerns axillary management. The explicit recommendation against sentinel lymph node biopsy for any PT subtype reflects the understanding that these tumours metastasize hematogenously rather than through lymphatic spread. This evidence-based position should help eliminate unnecessary axillary procedures that add morbidity without oncological benefit. The recommendation for histopathological examination of suspicious nodes before proceeding to axillary clearance provides a measured approach to the rare cases where nodal involvement occurs.

The guidelines also provide clarity on the limited role of adjuvant therapies. Adjuvant chemotherapy is not recommended for non-metastatic disease, supported by robust evidence showing no survival benefit (7). The approach to radiotherapy is more nuanced, with recommendations varying by subtype and risk factors. Radiotherapy is not recommended for benign tumours, and while generally not advised for borderline tumours, it may be considered in selected high-risk cases such as large tumours (>5 cm), infiltrative borders, or positive or close margins (<5 mm) when re-excision is not feasible. For malignant PTs, radiotherapy may be considered in large (≥5 cm) or multifocal tumours (5,8). In small solitary tumours, radiotherapy should only be considered if clear 5 mm margins cannot be achieved and further surgery is not possible, with re-excision being the preferred option. Recurrent disease is treated with wide local excision if feasible or mastectomy and radiotherapy may be considered after re-excision of malignant tumours if not previously given. A dose in the range of 50–66 Gy is recommended, and hypofractionation may also be considered. Before commencing radiotherapy, germline TP53 testing should be considered, given the potential risk of secondary malignancies in mutation carriers (9). It should be emphasized that although adjuvant radiation reduces the risk of local recurrence, it does not improve overall survival (6,10).

The guidelines also propose stratified surveillance protocols that represent a rational, resource-conscious approach to follow-up. For benign tumours, a patient-initiated clinical follow-up without imaging surveillance and routine breast screening is sufficient given their low recurrence risk. For borderline tumours, clinical examination and ultrasound every 6 months for 3 years, together with annual mammography, are recommended. Malignant tumours require more intensive surveillance with clinical examination every 6 months for 3 years, then annually in years 4–5, ultrasound every 6 months for 3 years, and annual mammography. Chest imaging, either chest X-ray or low-dose computed tomography (CT), is recommended every 6 months for 2 years and annually for years 3–5, reflecting the 20% risk of distant metastasis, predominantly to the lungs (11). Similarly preoperative staging in the form of low-dose thoracic CT is only recommended for patients diagnosed with malignant PTs (1). Fluorodeoxyglucose positron emission tomography/CT (FDG PET/CT), with the high sensitivity of malignant tumor detection and a comprehensive whole body image field of view, may be beneficial for high-risk patients to look for unexpected sites of metastases (12).

That said, the current guidance on imaging surveillance does not fully take into account patient age and breast density. Mammographic radiation may be potentially harmful in women under the age of 40, and therefore, annual mammography is only reasonable for women aged 40 years and above. In those patients, mammography should ideally be combined with ultrasonography in the presence of dense breasts. For women under 40, or for those of any age with extremely dense breasts and an elevated risk of recurrence, breast magnetic resonance imaging (MRI) should be considered as an adjunct, even though the guidelines do not specifically recommend MRI for routine postoperative surveillance as it has been reported to demonstrate superior diagnostic accuracy compared with mammography (95.8% vs. 70%) (13).

Despite the comprehensive nature of these guidelines, several important limitations must be acknowledged. The evidence base for PT management remains limited, with most recommendations graded as level IV or V evidence, reflecting reliance on retrospective cohort studies, case series, and expert opinion rather than high-quality randomized controlled trials. The rarity of these tumours makes prospective studies challenging, as illustrated by the single prospective radiotherapy study that required 10 years to recruit only 46 patients. Many of the key surgical margin recommendations, particularly the specific millimeter thresholds for different subtypes, are derived primarily from consensus expert opinion rather than robust comparative data. The heterogeneity in margin definitions across studies, with inconsistent categorization of “positive”, “close”, and “negative” margins, further complicates evidence synthesis. Additionally, long-term outcomes data remain limited, with many studies having relatively short follow-up periods that may fail to capture late recurrences or the full spectrum of treatment-related morbidity. Economic evaluation was not performed, and the guidelines acknowledge that optimal surveillance strategies and the benefits of adjuvant therapy require further investigation. These limitations underscore the urgent need for prospective registry data collection and multicenter collaborative studies to strengthen the evidence base for future guideline iterations.

At the same time, the development of clear management algorithms and patient information materials demonstrates the guidelines’ practical focus on implementation, and the endorsement by multiple professional organizations across the UK and internationally suggests broad acceptance of the evidence base and recommendations. The identification of research priorities, including evaluation of optimal margin widths, adjuvant therapy benefits, and genomic sequencing for metastatic disease, provides a roadmap for future investigation, while the call for national prospective audit and registry data collection addresses the critical need for outcome monitoring in these rare tumours.

The latest ABS guidelines are broadly aligned with other international recommendations, including the National Comprehensive Cancer Network (NCCN) guidelines (14), which advocate a minimum margin width of 10 mm for borderline and malignant PTs, while accepting narrower margins for benign lesions. However, when a 10 mm disease-free margin cannot be achieved, mastectomy is not mandated; instead, further management—including further surgery and the potential role of adjuvant radiotherapy—is determined on a case-by-case basis following discussion in a multidisciplinary consensus meeting.

Finally, recent real-world data reflect evolving treatment patterns that are consistent with current guidelines. A large population-based study (n=921) from the Netherlands demonstrated increasing rates of breast-conserving surgery, acceptance of surgical margins narrower than 10 mm, and greater use of adjuvant radiotherapy for malignant PTs (15).

Ultimately, these guidelines represent a significant achievement in standardizing care for PTs based on the best available evidence. By providing clear, graded recommendations while acknowledging areas of uncertainty, they offer practitioners a framework for consistent, appropriate management. The emphasis on multidisciplinary care, patient involvement in decision-making, and rational resource utilization reflects modern healthcare principles. Most importantly, these guidelines should help reduce the practice variation and overtreatment that have characterized PT management (1). For patients facing the diagnosis of these rare tumours, the availability of evidence-based, standardized care pathways offers reassurance that their treatment will be both appropriate and consistent with contemporary best practice. The implementation of these recommendations across breast and sarcoma services should lead to improved outcomes and reduced unnecessary interventions, ultimately benefiting both patients and healthcare systems.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Gland Surgery. The article has undergone external peer review.

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-385/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-385/coif). K.M. received research grant provided by Breast Cancer Charity, consulting fees from QMedical and Sebbin, and honoraria for offering academic and clinical advice to Merit Medical and QMedical corporations. He is a fractional shareholder of Datar Genetics stock. Furthermore, he owns shares in HCA Healthcare UK and OncoBotanica. The other author has 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.

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