Omission of radiotherapy in elderly women with early stage metaplastic breast cancer

PURPOSE: Multiple studies have evaluated the omission of radiation therapy (RT) in elderly women with invasive carcinoma; no studies to date have assessed this question for metaplastic breast cancer (MBC). This study is the only known study describing national practice patterns and addressing the impact of RT versus observation on survival in elderly women with T1-2N0 MBC.

METHODS: The National Cancer Data Base was queried (2004-2013) for women aged ≥70 years with T1-T2N0 MBC that underwent lumpectomy. Multivariable logistic regression ascertained factors associated with RT administration. Kaplan-Meier analysis evaluated overall survival (OS) between patients treated with or without postoperative RT. Cox proportional hazards modeling determined variables associated with OS. Propensity matching was performed in order to address indication bias.

RESULTS: Of 547 total patients, 176 (32%) underwent observation, and 371 (68%) received postoperative RT. Temporal trends revealed that withholding RT steadily declined over the studied time period. RT delivery was less likely in patients not undergoing hormonal therapy or those ≥80 years old. In both the overall population and following propensity matching, delivery of RT was associated with higher OS (p < 0.001 for both). On Cox multivariate analysis, poorer OS was independently associated with advancing age, higher T stage, high-grade disease, and omitting postoperative RT (p < 0.05 for all).

CONCLUSIONS: Although level I evidence exists to omit RT in select elderly women, this is the only study evaluating this notion for MBC. These results do not support the routine withholding of RT in T1-2N0 MBC owing to the independent association with worse survival.