Duration of adjuvant trastuzumab treatment in routine practice.

BACKGROUND Trastuzumab is used for the adjuvant (postoperative) treatment of (HER2)-positive early breast cancer. The duration of treatment is set at one year. The goal of our study was to examine the effective duration of trastuzumab treatment in routine clinical practice. PATIENTS AND METHODS We performed a retrospective review of all patients with early breast cancer, treated with trastuzumab at our hospital between 2005 and 2008. Data concerning patterns of use and safety were collected from patient charts and pharmacy records. RESULTS The cohort comprised of 96 patients, with a median age of 50 years (range=25-79 years). The majority of patients (63.5%) had node-negative disease. Besides trastuzumab, most patients underwent chemotherapy (before or after surgery). Trastuzumab was administered every three weeks and the median duration of treatment was 52 weeks (range=6-81 weeks). Only half of the patients received the monoclonal antibody for 52 weeks, 36.6% had therapy more than 52 weeks and 12.5% discontinued treatment before 52 weeks due to adverse effects (8.4%) and refusal (4.1%). Two (2.1%) patients discontinued trastuzumab therapy because of cardiotoxicity, a recognized side-effect of the monoclonal antibody. Regarding treatment durations of more than 52 weeks, 15/35 were due to the off-label use of trastuzumab in the neoadjuvant setting (before surgery). The 3-year rate of disease-free survival was 91.6%. CONCLUSION Half of the patients completed the 52-week treatment of trastuzumab after surgery for early breast cancer. Trastuzumab was well-tolerated and the rate of discontinuation due to cardiotoxicity was low, compared to published results.