Adjuvant Trastuzumab for 6 Months is Effective in Patients with HER2-positive Stage II or III Breast Cancer

Objective: The optimal duration of adjuvant trastuzumab treatment in patients with HER2-positive breast cancer is not known. The aim of this study was to evaluate the efficacy of 6 months of adjuvant trastuzumab treatment in patients with stage II or III HER2-positive breast cancer. Methods: The records of patients with HER2-positive stage II or III breast cancer who were admitted to the Breast Center of Taipei Medical University Hospital and Yuan's General Hospital between 2000 and 2008 were reviewed. All patients received adjuvant trastuzumab at an initial dose of 4 mg/kg followed by a maintenance dose of 2 mg/kg/week for 22 weeks in combination with chemotherapy. Results: A total of 51 patients were included with a mean age of 46.9 years. Approximately 55% of the patients had stage III disease. The mean follow-up time from initiation of treatment was 45.2 months (range, 0.9 to 85 months). During follow-up, 46 patients (90.2%) did not experience tumor recurrence. The mean estimated disease free survival was 80.2 months. The estimated 1-, 2-, 5-, and 7-year survival rates were 97.9%, 93.1%, 93.1%, and 93.1%, respectively. The most common adverse effects were gastrointestinal symptoms (21.6%), chills (17.6%), dizziness (9.8%), and bone pain (7.8%). No cardiac or hematologic adverse events occurred. Conclusion: Adjuvant therapy with trastuzumab for 6 months resulted in a clinical benefit in patients with HER2-positive breast cancer.