Small HER2-Positive Breast Cancer: Should Size Affect Adjuvant Treatment?

Introduction: The adjuvant trastuzumab trials largely excluded women with small, node-negative, HER2-positive breast cancers. Accordingly, limited data exist regarding the effect of trastuzumab in the management of these patients. Our aim was to assess the outcomes of, and treatments administered to, women with small (≤ 2 cm), node-negative, HER2-positive breast cancer in 4 Australian cancer centers.

Patients and methods: A retrospective analysis of data on all women with node-negative, HER2-positive breast cancers ≤ 2 cm diagnosed between 1 January 2001 and 31 December 2011 and treated at 4 cancer centers in Sydney, Australia was undertaken. The primary outcomes were recurrence-free survival (RFS) and overall survival (OS).

Results: In total, 128 patients with node-negative, HER2-positive breast cancers ≤ 2 cm were identified. Of these, 83 women (65%) received adjuvant trastuzumab which, in 96% of cases, was in addition to adjuvant chemotherapy. At 3-year follow-up, the RFS was 100% and 79.2% and the OS was 100% and 92.6% for women treated with, and without, trastuzumab, respectively. There were 14 recurrence events and 6 deaths in the study population. There were no significant differences in RFS and OS for the 46 women treated with, or without, trastuzumab for those with tumors ≤ 1 cm.

Conclusion: There is a growing body of evidence to support the use of adjuvant trastuzumab therapy in the management of small, node-negative, HER2-positive breast cancers. However, future studies with longer follow-up and prospective biomarker analysis might assist in clinical decision-making for this patient group.