Survival outcomes by hormone receptor expression in early-stage HER2-positive breast cancer.

Abstract

e12050 Background: The clinical heterogeneity seen in HER 2 positive breast cancer (BC), mostly related to hormone receptor (HR) expression has been suggested to underlie the variability of response not only to endocrine treatments, but also to anti-HER-2 therapies. Herein, we describe our single institution experience with clinical outcomes by HR expression in early HER 2 positive BC. Methods: An IRB-approved single-institution retrospective analysis was performed for 400 consecutive patients with non-metastatic HER 2 + BC treated at the Ohio State University Comprehensive Cancer Center from 2005-2015. Medical records were reviewed for clinic-pathologic, treatment, and survival information. Disease Free Survival (DFS) was defined as time from diagnosis to first recurrence (loco-regional or distant recurrence) including second primary BC or death. Overall survival (OS) was defined as time from diagnosis to death or last known follow up. OS and DFS estimates were generated using Kaplan Meier methods and compared using Log-rank tests. Cox proportional hazard models were used to calculate univariate and multivariate hazard ratios for OS and DFS. Results: a total of 180/400(45%) patients were diagnosed with HR positive disease. The mean age was 54.1y and patients were predominately white (267, 84%), post-menopausal (190, 60%) and presented with invasive ductal cancer (293, 92%). HR negative disease was significantly associated with high tumor grade (72% vs. 52%, p <0.0001) and lower BMI (27.6 vs 30.1, p 0.0218) compared to HR + tumors. The frequency of CNS metastases was not significantly different between both groups (8 (4%) in HR + vs. 8(6%) in HR –, p 0.9909). 173(96%) of HR + patients received anti-estrogen therapy with median duration of therapy of 40.9 months and 22(13%) received adjuvant ovarian suppression. There was no significant difference between the DFS and OS by hormone receptor expression (P= 0.7459 and 0.6518 respectively). However, higher number of HR negative patients undergoing neoadjuvant therapy achieved a complete pathologic response (pCR, 64% vs 44%, p 0.0092). pCR was prognostic for both DFS(p 0.0002) and OS (p 0.0008) in HR negative subgroup and not in HR + subgroup. Conclusions: The triple positive phenotype represents a distinct clinical subtype of HER 2 positive breast cancer associated with low tumor grade and lower frequency of pCR. Consistent with other studies, pCR was not prognostic of long term survival in triple positive disease. Future trials investigating the ER/ HER 2 cross talk are needed for this patient population.