Introduction
•Phyllodes tumors are rare fibroepithelial lesions.
–They comprise <1% of all breast malignancies.
–Surveillance, Epidemiology, and End Results Program (SEER) data report ~500 cases in the US annually [The SEER program is comprised of 18 population-based cancer registries around the US]
•They are characterized by hypercellular stroma growth into epithelial-lined cyst spaces
–While similar to fibroadenomas, suspicion for phyllodes tumor is based on large size, a rapid growth rate, and findings of stromal hyperplasia and atypia
•Phyllodes tumors are categorized as benign, borderline, and malignant tumors based on the degree of stromal hyperplasia and atypia (World Health Organization categorization)
•The National Comprehensive Cancer Network (NCCN) guidelines for management recommend wide excision with margins >/= 1cm (breast conserving surgery BSC), and recommend against axillary staging
•Routine use of radiation therapy (XRT) is not recommended given lack of randomized studies supporting its use
–Although the relatively high rate of local recurrence has generated interest in the potential role of XRT, there has been only one prospective study (Barth et al) and thus in the absence of better data, NCCN recommends consideration of XRT only if surgical management of a local recurrence would be especially morbid
•The objective of this study was to examine current patterns of care for treatment of phyllodes relative to the guidelines
Findings
•UsingSEER data, the authors identified patients (older than age 18) with a histologic diagnosis of malignant phyllodes tumors diagnosed between the years 2000 and 2012 and who underwent surgical therapy
•1238 patients were identified , and patient characteristics are outlined in table 1
–Mean age 50.2 years, median tumor size 4.8 cm
•56.9% underwent breast conserving surgery (BCS), 43.1% underwent mastectomy
–Tumor size was greater in women undergoing mastectomy versus BCS (66.6% vs 28.7% with size > 5cm)
•Nodal sampling was performed in 23.6%, and was more common in those undergoing mastectomy (40.9% vs 10.5%)
–Of those who had nodes examined, only 4% were positive (confirming that phyllodes only rarely metastasize to the lymph nodes)
•XRT was administered to 15.4% overall
–More common after mastectomy (18.8% vs 12.9%)
•Examination of temporal trends failed to show any difference in proportion of women who underwent BCS vs mastectomy during this time period, as well as rates of nodal examination. Rates of XRT increased over time for both BCS and mastectomy during this time period (5.6% to 25.0% after BSC, and 10.9% to 25.5% after mastectomy).
•Women were more likely to undergo mastectomy if they were older or had larger tumors, more likely to receive nodal evaluation if they were older, had a larger tumor size, or underwent mastectomy (strongest predictor), and receipt of XRT was associated with later years of diagnosis, larger tumor size, and nodal examination
Conclusions
•Examination of SEER data showed that about 50% of patients are treated with breast conservation (the appropriate treatment for phyllodes), there is an increasing use of XRT over the study period (despite absence of level 1 data supporting this practice), and about 1 in 4 women received axillary nodal staging despite guideline recommendations against this additional surgery
•As phyllodes has a low incidence, the findings may represent an educational gap in the surgical care of patients with these tumors
•Improving the use of current guidelines in routine practice, such as those from the NCCN, for both common and rare conditions, may help to ensure appropriate treatment, especially at institutions not routinely treating rare diseases such as phyllodes tumor.