Background: Disease-free survival (DFS) in patients with EBC has improved over time. Trials of systemic agents for adj rx of HER2+ BC, including chemotherapies (CT), endocrine, and HER2-targeted agents have reported improved DFS. This review is a high-level overview describing DFS improvements in adj rx HER2+ BC. Methods: Therapeutic agents listed in NCCN guidelines for adj rx HER2+ BC were evaluated for relative and absolute improvements in DFS. Information was derived from US product labels and publications. Hazard ratios, 95% CI, p-values, and DFS differences at 2 and 5 years (if available) are reported. Results: At 2−3 years, adj rx of HER2+ BC with CT and HER2 treatments reported DFS improvements of 4−5% and 0.9−11.3%, respectively. For hormone receptor positive (HR+) BC, unselected by HER2 status, extended adj letrozole had a 1.9% DFS improvement at 2 years; in HR+ HER2+ BC, extended adj neratinib had 4.5% DFS at 2 years. Conclusions: Relative and absolute improvements in DFS in the adj rx BC setting have been largely incremental and cumulative. Absolute improvements in DFS were 0.9−11.3% with CT, HER2 agents, and AIs. In the subset of HR+ / HER2-positive patients, neratinib showed higher DFS improvement compared to non-steroidal AIs. Similar hazard ratios did not always correspond to similar DFS improvements, possibly reflecting differences in baseline risks in the study populations.

*ITT; †HR+ ≤ 1 year from trastuzumab; ‡No pCR