Background: The aim of the present study was to evaluate clinicopathological characteristics of our early stagebreast cancer patients who are epidermal growth factor receptor 2 (HER2) overexpressed/ amplified (HER2+),the efficacy of trastuzumab treatment and survival results. Materials and
Methods: Patients with HER2- positiveearly stage breast cancer receiving adjuvant trastuzumab were investigated retrospectively. Clinicopathologicalfeatures of 210 patients and treatment outcome were analysed. To evaluate survival rates, the Kaplan-Meiermethod was used. Univariate and multivariate analyses were conducted with the Cox regression model.
Results:Mean age of the patients was 51.8, 71.9% being postmenopausal. Some 37.6% of patients were node negative,and 31% had T1 tumor size and 52.4% were positive for estrogen receptor. Of 210 patients, 89.5% completedplanned 52 weeks adjuvant trastuzumab treatment. The median follow up was 27.5 months (6.0-86.0 ). Relapsefree survival (RFS) was 68.0 months (95% CI: 62.1-74.0) and overall survival (OS) was 74.8 months (95%CI: 69.5-80.1). The 3 year OS for all patients was 92.0% and RFS was 79.6%. During follow up, relapse wasdetected at the rate of 14.3%. Trastuzumab associated cardiotoxicity was found at the rate of 3.3%. In univariateanalyses, larger tumor size and grade III were significantly associated (p<0.05) with RFS. Multivariate analysesof covariates displaying p<0.05 identified grade III as an independent prognostic factor.
Conclusions: In thepresent study, it was established that trastuzumab had a satisfactory safety profile and treatment efficacy as inother clinical studies and that among clinicopathological factors evaluated, only being grade 3 had a significanteffect on RFS. The occurrence of relapse with adjuvant trastuzumab makes it necessary to identify molecularpredictors, which will define this group better and help explain resistance to anti HER2 based therapies.