The effect of adjuvant treatment in small node-negative HER2-positive breast cancer: which subgroup will benefit?

Abstract Objective We conducted this study to evaluate whether patients with T1a/b, node-negative (N-), HER2-positive (HER2+) breast cancers benefited from adjuvant therapy, and explored better treatment strategies for these patients. Methods Patients with T1a/b, N-, HER2+ breast cancers during 2000–2004 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. The Gray test was used to evaluate breast cancer specific death (BCSD) and non-BCSD. To identify patients more suitable for chemotherapy, subgroup analyses were conducted according to tumor size and estrogen receptor (ER) status, and a plot of hazard rate of death (HRD) was drew to present the changes of BCSD. Results A total of 2940 patients with T1a/b, N-, HER2+ breast cancers were included, more patients in T1b group received chemotherapy compared to T1a group (65.18% versus 29.30%, P Conclusion Chemotherapy, which is mainly decided by tumor size, fails to render survival benefits for patients with T1a/b, N-, HER2+ breast cancers. ER status, rather than tumor size, is important for clinicians to make adjuvant treatment decisions. The peak of BCSD occurs in 2-5 years after diagnosis, and an at least 5-year follow-up is recommended for these patients.