Abstract
BackgroundOnly few studies, with small patient cohorts, have evaluated the effect of radiotherapy (RT) for metaplastic breast cancer (MBC). Hence, it is important to investigate the role of RT in MBC survival using a large population-database.MethodsA retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) from 1973 to 2015 was performed. We compared MBC patients with or without RT for overall survival (OS) and breast cancer-specific survival (BCSS) using univariate and multivariate Cox proportional hazard regressions before and after propensity score matching (PSM).ResultsFrom a total of 2267 patients diagnosed with MBC between 1998 and 2015, 1086 (47.9%) received RT. In the multivariate analysis before PSM, RT provided a better OS (HR 0.73; 95% CI 0.61–0.88; p = 0.001) and BCSS (HR 0.71; 95% CI 0.58–0.88; p = 0.002). Multivariate analyses after PSM (n = 1066) confirmed that patients receiving RT (n = 506) survived longer than those without RT (OS, HR 0.64; 95% CI 0.51–0.80; p < 0.001 and BCSS, HR 0.64; 95% CI 0.50–0.83; p = 0.001). A longer OS was observed when RT was given to older patients (p = 0.001) and in case of large tumor size (p = 0.002). Intriguingly, patients with N0 stage showed better OS after RT (HR 0.69, P = 0.012).ConclusionsOur findings support the beneficial effect of RT for MBC patients. In particular, older patients or with large tumor size have a greater survival benefit from RT. In conclusion, we have assessed the importance of the use of RT in MBC as survival factor and this could lead to the development of guidelines for this rare sub-type of tumors.
Highlights
Few studies, with small patient cohorts, have evaluated the effect of radiotherapy (RT) for metaplastic breast cancer (MBC)
Was observed when RT was given to older patients (≥ 60 years old) (HR 0.614, P = 0.001) and those with larger tumor size (HR 0.593, P = 0.01) (Fig. 3a, b)
Our subgroup analyses revealed that RT significantly improved overall survival (OS) in older MBC patients
Summary
With small patient cohorts, have evaluated the effect of radiotherapy (RT) for metaplastic breast cancer (MBC). It is important to investigate the role of RT in MBC survival using a large population-database. Metaplastic breast cancer (MBC) is a rare pathologic entity of the mammary gland accounting for about 0.2– 2% of breast cancer diagnoses and is generally associated with poor overall survival (OS) [1,2,3]. In 2010, MBC was defined as a unique histologic subtype by the World. In the recently revised National Comprehensive Cancer Network (NCCN) guidelines, metaplastic carcinoma, defined as more than 10% of the tumor phenotype, is an independent prognostic variable; the guidelines
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