Abstract P4-12-02: Adjuvant trastuzumab improved the prognosis of HER2-positive early breast cancer: Single institutional cohort study from clinical practice

Abstract

Abstract Background: Trastuzumab-containing regimens for the adjuvant treatment of human epidermal growth factor receptor 2 (HER2)-positive early breast cancer significantly improved the prognosis. However, most data showing the effects of trastuzumab come from clinical trials. Aims: To evaluate the efficacy of the adjuvant trastuzumab in the clinical practice, the prognosis of HER2-positive early breast cancer was investigated according to the adjuvant treatment with or without trastuzumab. Methods: Among 2548 women who underwent surgery for primary breast cancer in our department between 2000 and 2011, 315 patients had HER2-positive tumors. A total of 293 patients aged 75 or younger with invasive HER2-positive breast cancer were included in this study. The associations between clinicopathological characteristics, adjuvant therapy and relapse-free survival (RFS) were examined. The RFS was estimated using the Kaplan-Meier method, and independent predictors were assessed using proportional cox hazard models. Results: 113 (38.5%) patients ware treated with chemotherapy alone (Cohort A), 100 (34.1%) patients were treated with chemotherapy and trastuzumab (Cohort B) and 80 (27.3%) patients received neither chemotherapy nor trastuzumab (Cohort C). The administration of adjuvant trastuzumab significantly increased in 2007. The prognosis of the patients treated in 2007-2011 was significantly better than that of patients treated in 2000-2006 (p=0.0011). The use of adjuvant trastuzumab was significantly associated with longer RFS (p=0.0286). The improvement of RFS by using trastuzumab was significant in node-positive patients. The patients in Cohort C had mainly node negative and small tumors. RFS of the patients treated of Cohort B was significantly more favorable than that of Cohort A. However, RFS of Cohort C was not statistically different from that of Cohort B, probably due to the early stage of Cohort C. In univariate analysis, larger tumor size (T2, 3), lymph node metastasis, lymphovessel invasion and absence of trastuzumab were related to relapse. In multivariate analysis, factors related to relapse were lymph node metastasis and absence of trastuzumab. Univariate and multivariate analysis for relapse-free survivalFactorsUnivariate analysis Multivariate analysis HR95% CIP valueHR95% CIP valueTumor sizeT2, T3 vs. T13.101.69-5.850.00021.820.87-3.950.1131LN meta.positive vs. negative4.372.26-8.84<0.00012.831.26-6.490.0116Histological grade3 vs. 1, 20.770.42-1.440.4199 lypositive vs. negativ3.401.87-6.25<0.00011.430.67-3.100.3538ERpositive vs. negativ0.930.50-1.650.7638 PRpositive vs. negativ0.970.50-1.760.8885 adjuvant chemotherapy 1.570.79-3.490.207 adjuvant trastuzumab 0.410.17-0.880.02070.410.16-0.900.0258LN meta.; lymph node metastasis, ly; lymphovessel invasion ER; estrogen receptor, PgR; progesterone receptor Conclusions: Use of adjuvant trastuzumab improved the prognosis of HER2-positive early breast cancer in clinical practice. Citation Format: Akiyoshi S, Ishida M, Koga C, Nakamura Y, Taguchi K, Ohno S, Tokunaga E. Adjuvant trastuzumab improved the prognosis of HER2-positive early breast cancer: Single institutional cohort study from clinical practice. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-12-02.