Abstract 304: Predictive factors of pathological complete response by neoadjuvant chemotherapy for operable breast cancer

Abstract

Abstract Background: Nonanthracycline regimens with taxanes have become to be used more frequently than before. Thus, it has become important to consider sensitivities to these two drugs in individual patients. Aim: To examine the association between the pathological response of each regimen and several pathological factors and whether individualized treatment based on HER2 may improve the overall pathological effects. Patients and methods: 1) Retrospective study: 170 patients treated with standard regimens consisted of anthracycline and/or taxan prior to surgery. 2) Prospective study: 18 patients with HER2 overexpression received 4 cycles of anthracycline and cyclophosphamide (AC), while 45 pathients without HER2 expression received 4 cycles of docetaxel and cyclophosphamide (TC). For these 2 studies, the overall pCR rates were examined. The association of pCR with pathological factors including estrogen- and progesterone-receptor (ER and PgR), HER2, nuclear grade, Ki-67, P-53 and Topoisomerase IIα (TopoIIα) etc. were also examined. Results: 1) The overall pCR rate was 24.2 % (41/170). Multivariate analysis with factors revealed that ER and nuclear grade were significantly associated with pCR. 2) The overall pCR rate was 36.5% (23/63), with pCR rates of 27.8% (5/18) and 40.0% (18/45) for the AC and TC regimens, respectively. TC regimen induced a pCR in most triple-negative cancer cases (15/19). Only low expression of ER maintained statistical significance as a predictor of pCR for the TC regimen. Conclusions: Individualized HER2-based treatment improved the efficacy of neoadjuvant chemotherapy, probably because HER2 is, at least at present, the most promising predictor for the efficacy of anthracyclines. Further studies with predictive factors including TopoIIα by FISH are now under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 304. doi:10.1158/1538-7445.AM2011-304