A Review of the Management of T1a/bN0 HER2-Overexpressed Breast Cancer

Small node-negative breast cancers measuring less than 1 cm (pT1a/bN0) are generally associated with a favorable prognosis. However, as many as 10% of these breast cancers exhibit human epidermal growth factor receptor 2 overexpression and/or amplification (HER2+). Chemotherapy + trastuzumab is the accepted adjuvant therapy for early HER2+ breast cancers as it lowers the risk of recurrence and mortality, but virtually all patients enrolled in the pivotal trials for this therapy had a higher stage of disease. Several large retrospective reviews have reported a lower overall survival among HER2+ cases in the pT1a/bN0 patient group. The use of chemotherapy with trastuzumab has increased significantly despite the lack of direct evidence for the efficacy of trastuzumab in pT1a/bN0 breast cancers. This review addresses the current data regarding the prognosis of pT1a/bN0 breast cancers and outcomes of patients receiving HER2-targeted therapy.