Material and Method: The authors reviewed retrospectively of newly diagnosed non-metastatic breast cancer patients at the Faculty of Medicine, Chiang Mai University between January 2004 and December 2007. Comparisons were made between the two cohorts, women who did not receive adjuvant trastuzumab (100 patients) and women who received adjuvant trastuzumab (14 patients).

Results: The median follow-up time was 4.7 years. Four-year relapse-free survival (RFS) and overall survival (OS) in patients receiving trastuzumab was 92.3% and 100%, respectively. In the cohort of HER-2 positive patients who did not receive trastuzumab, the 4-year RFS in this group was 68.2% and 4-year OS was 87.8%. The difference was not statistically significant between the 4-year RFS rates (p = 0.103) and the 4-year OS rates (p = 0.214). By multivariate Cox regression analyses, only nodal status was identified as the independent predictors for superior RFS (hazard ratio 2.93; 95% CI, 1.07 to 5.88; p = 0.034) and none of the clinical parameters were significant predictors for 4-year overall survival.

Conclusion: A hospital-based analysis of adjuvant Trastuzumab use in our center does not demonstrate the different treatment outcome. However, there is a trend of favorable outcome in the group receiving adjuvant trastuzumab.

Keywords: Breast cancer, Adjuvant trastuzumab, Retrospective study