Postmastectomy Radiation for N2/N3 Breast Cancer: Factors Associated with Low Compliance Rate

Abstract

The National Comprehensive Cancer Network and American Society of Clinical Oncology guidelines recommend postmastectomy radiation therapy (PMRT) for women with N2/N3 breast cancer. We examined the compliance rate of PMRT using the National Cancer Data Base and determined what factors are associated with low compliance rate with PMRT. The National Cancer Data Base, comprising 2,720,368 breast cancer cases diagnosed between 1998 and 2011, was evaluated. From this database, 56,990 women with N2/N3 diseases were evaluated. Statistics used include chi-square test, 2-sample t-test or Wilcoxon rank-sum test, and multivariate analysis. Mean age of the patients was 58 years and median follow-up was 61 months. The majority of patients were from a comprehensive community cancer programs (59%), were Caucasian (81%), had health insurance (96%), resided in urban communities (98%), and had no comorbidities (83%). Approximately 82% received chemotherapy, but only 65% had PMRT. Factors associated with PMRT are tumor grade (p = 0.03), regional lymph node surgery (p = 0.03), readmission within 30 days of surgical discharge (p = 0.03), receipt of chemotherapy (p < 0.01) and hormonal therapy (p < 0.01), and 30-day mortality (p < 0.01). Socioeconomic variables, such as facility type (p = 0.85), facility geographic location (p = 0.27), race/ethnicity (p = 0.12), insurance status (p = 0.10), income level (p = 0.43), education level (p = 0.86), residential location (p = 0.83), and comorbidities (p = 0.83) were not contributory factors. Independent variables predicting compliance with PMRT include receipt of chemotherapy (odds ratio = 4.55; p < 0.01), readmission within 30 days after surgery (odds ratio = 1.14; p = 0.01), and alive within 30 days after surgery (odds ratio = 1.55; p = 0.04). One third of patients with N2/N3 disease did not receive PMRT. Socioeconomic variables were not contributory factors. Noncompliance with PMRT is related to lack of receipt of chemotherapy, nonreadmission, or death within 30 days after surgery.