Effect of adjuvant radiotherapy on overall survival and breast cancer-specific survival of patients with malignant phyllodes tumor of the breast in different age groups: a retrospective observational study based on SEER

Abstract

PurposeMalignant phyllodes tumor of the breast (MPTB) is a rare type of breast cancer, with an incidence of less than 1%. The value of adjuvant radiotherapy (RT) for MPTB has been controversial. The aim of the study was to explore the effect of radiotherapy on the long-term survival of female patients with MPTB at different ages.MethodsFemale MPTB patients were selected from the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2020. A Kaplan–Meier survival analysis was conducted to investigate the value of RT for the long-term survival of MPTB patients in different age groups. Additionally, univariate and multivariate Cox regression analyses were performed for overall survival (OS) and breast cancer-specific survival (BCSS) of MPTB patients. Furthermore, propensity score matching (PSM) was also performed to balance the differences in baseline characteristics.Results2261 MPTB patients were included in this study, including 455 patients (20.12%) with RT and 1806 patients (79.88%) without RT. These patients were divided into four cohorts based on their ages: 18–45, 46–55, 56–65, and 65–80. Before adjustment, there was a statistically significant difference in long-term survival between RT-treated and non-RT-treated patients in the younger age groups (age group of 18–45 years: OS P = 0.019, BCSS P = 0.016; age group of 46–55 years: OS P < 0.001, BCSS P < 0.001). After PSM, no difference was found in long-term survival of patients in both younger and older groups regardless of whether they received RT (age group of 18–45 years: OS P = 0.473, BCSS P = 0.750; age group of 46–55 years: OS P = 0.380, BCSS P = 0.816, age group of 56–65 years: OS P = 0.484, BCSS P = 0.290; age group of 66–80 years: OS P = 0.997, BCSS P = 0.763). In multivariate COX regression analysis, RT did not affect long-term survival in patients with MPTB.ConclusionThere is no evidence that long-term survival of MPTB patients in specific age groups can benefit from RT.