Purpose: Optimal duration of adjuvant trastuzumab therapy in early-stage HER2-positive, lymph node-negative breast cancer is unknown. To establish this, we compared 1-year and 9-week trastuzumab regimens in HER2-positive, lymph node-negative early-stage breast cancer patients.
Methods: We retrospectively analyzed 4374 breast cancer patients. There were 181 early-stage, lymph node-negative breast cancer patients who were treated with adjuvant trastuzumab for either 9-week or 1-year schedule. A total of 101 patients received trastuzumab for 9 weeks and the remaining 80 patients received this adjuvant therapy for 1 year. Disease free survival (DFS) and overall survival (OS) rates of both groups were calculated.
Results: There was no difference between groups according to OS. Five-year OS rates were 95.5% in the 9-week group and 93.3% in the 1-year group (p=0.78). DFS was affected by age, having tamoxifen therapy and disease stage. Nine-week trastuzumab group was superior to 1-year group and 5-year DFS rates were 91% in 9-week group and 81.2% in 1-year group (p=0.02). However, the 1-year group had more stage II patients than the 9-week group. We did not find any difference between groups regarding developing congestive heart failure.
Conclusion: It appeared that 9-week trastuzumab treatment was not inferior to 1-year trastuzumab treatment in early-stage, lymph node-negative breast cancer patients.