Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer have a higher risk of locoregional recurrence (LRR), even in the setting of early stage, lymph node-negative disease. In this sequential, retrospective study, the authors evaluated whether adjuvant trastuzumab was associated with reduced LRR in women with lymph node-negative, HER2-positive disease who received breast-conservation therapy (BCT).
By using an institutional database, 197 women were identified who had lymph node-negative, HER2-positive breast cancer measuring ≤5 cm diagnosed between 2002 and 2008 and who received BCT, including whole-breast irradiation. Two cohorts were compared: 70 women who did not receive trastuzumab (the no-trastuzumab cohort) and 102 women who did receive trastuzumab (the trastuzumab cohort). Kaplan-Meier methods were used to estimate LRR-free survival.
The 2 cohorts were similar in age, tumor size, histology, and hormone receptor status. Chemotherapy was received by 73% of the no-trastuzumab cohort and by 100% of the trastuzumab cohort. In both groups, 99% of patients completed radiotherapy with a median dose of 60 Gray. The median recurrence-free follow-up was 86 months for the no-trastuzumab cohort and 47 months for the trastuzumab cohort. The 3-year LRR-free survival rate was 90% (95% confidence interval, 83%-97%) for the no-trastuzumab cohort and 99% (95% confidence interval, 97%-100%) for the trastuzumab cohort. In the no-trastuzumab cohort, LRR occurred in 7 patients (median time to LRR, 14 months). In the trastuzumab cohort, there was 1 LRR at 14 months.
Even among women with lower risk breast cancer, the relatively high locoregional failure rates associated with positive HER2 status could be reduced markedly with adjuvant trastuzumab chemotherapy. Within 3 years, a 10% LRR rate without trastuzumab and a 1% LRR rate with trastuzumab were observed in women with lymph node-negative disease who received BCT. Cancer 2012. © 2011 American Cancer Society.