Adjuvant chemotherapy in T1a/bN0 HER2-positive or triple-negative breast cancers: application and outcomes.

We assessed practice patterns and the impact of systemic adjuvant therapy on human epidermal growth factor receptor 2 (HER2)-positive or triple-negative, node-negative breast cancers up to 10 mm in size. Records of 161 patients identified among 1415 cases diagnosed in our institutions between 2000 and 2010 were assessed for factors associated with recommendation for chemotherapy and survival outcomes. Adjuvant chemotherapy was recommended in 53% of patients, more commonly in patients with younger age, stage T1b, high grade, HER2+/ER- status and diagnosis after 2006. With a median follow-up of 54 months, the 5-year cumulative incidence of recurrence was 5.3% and overall survival was 93.2%. Age less than 40 and presence of lymphovascular invasion (LVI) were associated with higher risk of recurrence. In a univariate analysis administration of adjuvant chemotherapy was not associated with a significantly better recurrence rate (P = 0.33).