Abstract P3-11-13: Change of Ki-67 after long course of neoadjuvant chemotherapy as prognostic factors in patients with stage II, III triple negative breast cancer

Abstract

Abstract Background: Triple negative breast cancer (TNBC) shows poor prognosis despite their higher response rate to neoadjuvant chemotherapy (NAC). Response to NAC such as pathologic complete response (pCR) is a well-known useful prognostic marker for relapse and overall survival. Pre-chemotherapy baseline higher Ki-67 is a positive predictive marker for higher pCR rate but a negative prognostic marker for relapse free survival (RFS) and overall survival (OS). After short course of NAC, Ki-67 index changed in response to the treatment. The purpose of this study is to investigate the prognostic role of Ki-67 index change between before and after the long course of NAC in TNBC patients. Patients and Methods: Patients with clinical stage II or III breast cancer treated with NAC at Seoul National University Hospital were enrolled and their clinicopathological findings including Ki-67 index were reviewed retrospectively. The definition of Ki-67 threshold of high was ≥14% in current study. TNBC definition was adopted from 2011 St Gallen Consensus Panel. Results: From Jan 2009 to Dec 2010, a total of 183 patients received NAC. Among them, 46 (25.1%) were TNBC. The pCR rate (19.6% vs 9.5%, P=0.069) and the objective response rate (complete response + partial response) (76.1% vs 70.8%, P=0.153) were higher in TNBC group than in non-TNBC group. The RFS was not different between the two groups (3 year 77.3% vs 75.4%, P=0.877). The change of Ki-67 index from high (≥14%) to low (<14%) was significantly associated with longer RFS in only in TNBC group. As for TNBC patients with high Ki-67 index at diagnosis, RFS of those whose Ki-67 index changed to low after NAC were significantly longer than that of whose Ki-67 index remained high (3 year RFS 87.2% vs 54.5%, P=0.036). In non-TNBC group, change of Ki-67 index was not significantly associated with RFS (P=0.245). The initial Ki-67 index itself (high vs. low) was not associated with RFS in both TNBC and non-TNBC group (P=0.726 and P=0.523 respectively). Conclusion : The change of Ki-67 index from high to low is associated with longer RFS in TNBC. Ki-67 index change between before and after the NAC can be used for further discrimination of TNBC as a prognostic marker. Citation Format: Yaewon Yang, Tae-Yong Kim, Seock-Ah Im, Bhumsuk Keam, Kyung-Hun Lee, Sae-Won Han, Do-Youn Oh, Tae-You Kim, Hyeong-Gon Moon, Wonshik Han, In Ae Park, Dong-Young Noh. Change of Ki-67 after long course of neoadjuvant chemotherapy as prognostic factors in patients with stage II, III triple negative breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-11-13.