Factors Associated With Guideline-Concordant Use of Radiotherapy After Mastectomy in the National Comprehensive Cancer Network

Purpose We examined the rates and determinants of appropriate and inappropriate use of postmastectomy radiotherapy (PMRT), as defined by the National Comprehensive Cancer Network (NCCN) practice guidelines, among women with Stage I-II breast cancer (American Joint Committee on Cancer, 5th edition). Methods and Materials Using clinical characteristics, 1,620 consecutive patients at eight NCCN institutions who had undergone mastectomy between July 1997 and June 2002 were classified into three cohorts according to whether the guidelines (1) recommended PMRT, (2) recommended against PMRT, or (3) made no definitive PMRT recommendation. We defined the absence of PMRT in the first cohort as underuse and receipt of PMRT in the second cohort as overuse. Multivariate logistic regression analysis was applied to investigate the association of clinical and sociodemographic factors with PMRT. Results Overall, 23.8% of patients received PMRT. This included 199 (83.6%) of 238 in the “recommend PMRT” cohort, 58 (5.6%) of 1,029 in the “recommend against PMRT” cohort, and 127 (38.6%) of 329 in the “consider PMRT” cohort. The only factor associated with underuse in the “recommend PMRT” cohort was nonreceipt of chemotherapy (odds ratio [OR], 0.08; p