Effect of adjuvant trastuzumab (Tadj) therapy (Tx) for early-stage breast cancer (ESBC) on demographics, survival and likelihood of durable complete response (DCR) of HER2+ metastatic breast cancer (HMBC): A 15-year study.

e11604 Background: We hypothesize that in addition to its powerful effect on the outcome of patients (pts) with HESBC, Tadj has also altered the epidemiology and prognosis of pts with HMBC. Methods: We constructed a database of 742 pts treated with Tadj (224 HMBC since 2000, 518 HESBC [trials 2001-2004, routinely since 2005]). We conducted a cohort analysis of all HMBC treated between January 2000 and December 2014. We compared incidence of de novo (DN) versus relapsed (R) HMBC, and overall survival (OS) between DN versus R and across cohorts. Results: Cohort 1 (Jan 2000 – Dec 2004: 67 pts), Cohort 2 (Jan 2005 – Dec 2009: 85 pts), Cohort 3 (Jan 2010 – Dec 2014: 72 pts). The proportion of pts with R HMBC decreased (I-84% vs. II-64% vs. III-57%) whereas the proportion with DN increased (I-16% vs. II-36% vs. III-43%, p < 0.01). DN pts had significantly improved median OS (58m, [95%CI: 26-90]) compared to R (29m [21-37]), p < 0.001 log rank. Median OS improved from Cohort 1 to Cohort 3. Best Objective Respons...