Abstract P3-14-12: Risk factors for local regional recurrence in patients undergoing breast conserving surgery following neoadjuvant chemotherapy and validation of the MD Anderson prognostic index

Abstract

Abstract Background: Breast conserving surgery (BCS) is a primary goal of neoadjuvant chemotherapy (NAC) in patients with locally advanced breast cancer, especially with recent improvements in tumor response. Patient selection for BCS following NAC may be different than classic local regional recurrence (LRR) risk factors. Here we investigate risk factors for LRR and attempt to validate the MD Anderson Prognostic Index (MDAPI) for LRR in a single institution series. Methods: Data were analyzed for 178 consecutive patients treated at one institution who underwent NAC followed by BCS and whole breast radiotherapy between the years 1999 and 2011. Using univariate and multivariate analysis, multiple clinicopathologic factors were investigated, as well as the subgroups of the MDAPI. Chi-square tests were used to compare the LRR-free survival rates between subgroups. Results: The median follow-up was 70.33 months and the 5-year LRR-free survival was 93.18%. Multivariate analysis demonstrated that clinical stage and pathologic stage were both statistically significant for LRR-free survival, while pattern of residual disease was of borderline statistical significance. The MDAPI was not significantly associated with LRR-free survival (MDAPI low 93.80%, Intermediate 88.23%, High 88.89%). Five-Year Local Regional Recurrence -Free Survival According to Clinicopathologic Factors # Patients5yr LRR-Free SurvivalPathologic Stage p = 0.03301580.0%14292.5%27692.5%3994.6%pCR38100%Clinical Stage p = 0.0291580.0%213796.3%33883.8%MDAPI Score P = 0.506Low (0 or 1)12993.80%Int (2)3488.23%High (3)988.89%*MDAPI Score Factors cN Stage P = 0.305cN0-N116593.3%cN2-N31070%LVI P = 0.453No-LVI15793.5%Yes-LVI2390.9%pT>2cm P = 0.158Residual Tumor Morphology P = 0.055Multifocal Resid Tumor5996.5%Solitary Mass6690.6%No Resid Tumor5394.3%*These factors make up the MDA Prognostic Index Conclusion: Overall the 5-year LRR-free survival was high at 93.18%, which compares favorably to similar neoadjuvant patient cohorts who receive mastectomy instead of BCS. Our analysis indicates clinical stage and pathologic stage are significant in predicting LRR. Of the four predictive factors utilized by the MDAPI, only multifocal residual disease showed weak predictive power (p = 0.055) in our population; however, it correlated with higher LRR-free survival, the opposite of its indication in the MDAPI. The MDAPI was not useful in our patient population; the risk groups did not significantly correlate with LRR-free survival. This may be secondary to low total number of recurrence events and also the small number of patients in the MDAPI-high group (9 patients had an MDAPI score of 3, and none had a score of 4). As further data emerge regarding biology of tumors and recurrence, it may be a combination of molecular profiling and residual cancer burden that is a better predictor for LRR. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-14-12.