Residual cancer burden as a prognostic factor in a large series of neoadjuvant chemotherapy. Subgroup analysis per molecular surrogated subtypes

Abstract

Background: Neoadjuvant chemotherapy offers the possibility to test chemo sensitivity in vivo. pCR is a good surrogate of survival. Other measures of pathological response include de residual cancer burden (RCB). The aim of our study is to assess prognostic factors of survival including RCB. Method(s): 488 breast cancer (BC) patients treated with NATC based on anthracyclines and taxanes with trastuzumab in HER-2 positive between 2009 and 2016 at a single Institution. Chi-square test was run for the univariate analyses and a cox-regression was performed regarding prognostic factors. Survival was calculated with Kaplan-Meier survival plots since the start of NATC to the first documented disease recurrence (DDFS) or overall survival (OS) by using IBM SPSS version 23. Result(s): Mean age was 51.13 (24-84). After a follow up of 63 (4-129) months there have been 14 (2.9%) local recurrences; 55 (11.3%) distant recurrences and 56 deaths (11.4%), 50 due to BC progression (10.2%). In the univariate analyses those factors related to distant recurrence were histology ductal vs lobular: 14.2 vs 35.7%, p: 0.032; molecular subtype: luminal A (15.2%) vs luminal B (14.2%) vs luminal B Her2 (11.8%) vs HER2 enriched (7.7%) vs triple negative (TN) (22.8%), p: 0.042; TstageT0 (0%), T1(12.5%), T2(12.3%), T3 (18.8%) and T4 (23.9%), p: 0.006; N stage N0 (9.6); N1 (12.8), N2 (17.5) and N3(27.3%), p = 0.063;pTstage pT0 (8.5%), pTis (9.7) pT1a+b(7.5%)pT1c(20.3 %), pT2(21.8%), pT3 (29.2%) and pT4 (100%), p = 0.000; pN stage pN0 (8.2); pN1mic (0%), pN1 (16.8), pN2 (32.2) and pN3(42.3%), p = 0.000 and the RCB 0 (3.2%) vs I (7.1%) vs II (16.5%) vs III (23.4%), p: 0.0001. The estimated 5y DDFS was for RCB0: 100%; RCBI: 98%; RCBII: 85% and RCBIII: 68%. The HR for RCB was 1.4 (95%IC, 1.2-1.6), per subgroups the log rank was for luminal A: 3.4, p: 0.330; for luminal B: 10.6, p: 0.03; for luminal B Her2: 7.9, p: 0.04; for Her2 enriched: 25, p: 0.000 and for TN 16, p: 0.003. Conclusion(s): In our large series the RCB is reproducible as a surrogate of survival special in those chemo sensitive tumors such as Her2 and triple negative ones. Legal entity responsible for the study: The authors. Funding(s): Has not received any funding. Disclosure: All authors have declared no conflicts of interest.Copyright © 2019 European Society for Medical Oncology