Time trends in the use of adjuvant chemotherapy (CTX) and outcomes in women with T1N0 breast cancer (BC) in the National Comprehensive Cancer Network (NCCN).

Abstract

1006 Background: The role of adjuvant CTX in women with small BC is controversial. Here we analyze time trends of CTX use and outcomes in women with T1N0 BC treated at NCCN cancer centers. Methods: 8917 women were identified who received surgery or systemic therapy at an NCCN center with T1a, T1b or T1c N0 M0 BC between 2000-09. Tumors were grouped by biologic subgroups by hormone receptor (HR) and HER2 status and T subgroups (T1a, T1b, T1c). Primary endpoints were receipt of adjuvant CTX (± trastuzumab) and BC specific survival (BCSS). Chi-square, Cochran Armitage trend, Kaplan Meier estimates, log-rank test and Cox hazard proportional regression were used for analysis. In this report we focus on T1a/b results (N=4113). Results: Median follow up time was 5.5 years (range, 0.7-12.7). CTX use differed according to biologic and T subgroups, with significant changes over time (Table). In 2009, more than 50% of patients (pts) with HER2+ and HR-2- T1a/b breast cancers received CTX (± trastuzumab). The table lists use of CTX by year and subset and the 5 year BCSS for pts treated and not treated with CTX. Conclusions: A high proportion of pts with HER2+ and HR-HER2- T1N0 breast cancers received adjuvant CTX, with a sharp increase in use of CTX among HER2+ over the past decade. Use of CTX is higher in T1b compared to T1a tumors. In this study, women with T1a and T1b tumors have an excellent prognosis without CTX at 5 Yr. Careful examination of cutoffs for absolute benefit sufficient to recommend CTX is warranted. [Table: see text]