Observational study on adjuvant trastuzumab in HER2-positive early breast cancer patients.

Aim: This observational study investigates the use of adjuvant trastuzumab (AT) in HER2-positive breast cancer patients in a real-life setting, focusing on relapse and discontinuation rates.

Patients & Methods: Data on a group of HER2-positive patients collected from 13 oncology centers of northeast Italy were analyzed.

Results: In total, 1245 patients were analyzed. 13.1% of patients were excluded from AT because of comorbidities, age, tumor stage, refusal or other reasons; 8.2% of patients who received AT interrupted the therapy, mainly for toxicity. Overall the relapse rate was 10.9% in the AT-treated population versus 22.6% in nontreated patients (follow-up: 37.4 and 62.1 months, respectively). Disease-free survival (DFS) was lower in AT-relapsed patients than in not-relapsed. Statistical analysis showed a correlation between DFS and estrogen receptor status in AT-treated patients.

Conclusion: Relapse rates are lower in clinical setting compared to clinical trials. Overall, AT is effective in HER2-positive early-stage breast cancer patients.