The Impact of Adjuvant Chemotherapy on the Long-Term Prognosis of Breast Malignant Phyllodes Tumors: A Propensity Score-Matched Study.

Background: Malignant phyllodes tumors (MPTs) are rare breast tumors with high risks of local recurrence and distant metastasis. Surgical intervention is the primary treatment, but the effectiveness of adjuvant therapies is uncertain. This study was designed to analyze the prognostic risk factors associated with MPTs and evaluate the efficacy of postoperative adjuvant chemotherapy.

Patients and methods: Patients who were first diagnosed with MPT without distant metastasis and received R0 resection surgery between 1999 and 2023 were included in the present study and stratified into 2 groups: chemotherapy and nonchemotherapy groups. Propensity score matching (PSM) was used to balance baseline characteristics between groups. Kaplan-Meier curves were used to estimate local recurrence-free survival (LRFS) and overall survival (OS). Cox proportional hazards analyses (univariate and multivariate) were conducted to identify prognostic risk factors.

Results: We conducted a study involving 145 patients, 31 of whom underwent a total of 12 different chemotherapy regimens following initial surgical resection. Most patients received chemotherapy regimens primarily consisting of anthracyclines, including anthracycline + ifosfamide (AI) or anthracycline + cyclophosphamide/docetaxel (AC-T) regimens. After a median follow-up of 54.5 months, 37 (25.5%) patients experienced local recurrence and 24 (16.6%) experienced distant metastasis. No significant difference was detected in the rates of local recurrence or distant metastasis between the 2 groups. Axillary lymph node positivity was the only risk factor for LRFS, whereas older age, larger tumors, axillary lymph node positivity, local recurrence, and distant metastasis were significantly associated with worse OS. Chemotherapy did not emerge as a protective factor for LRFS (P=.501) or OS (P=.854). After PSM, patients in the chemotherapy group did not exhibit better 5-year LRFS (P=.934) or 5-year OS (P=.328).

Conclusions: According to our retrospective evaluation, postoperative adjuvant chemotherapy was not associated with improved survival in patients with MPTs without distant metastasis.