Abstract P6-09-06: The impact of molecular status on survival outcomes for invasive micropapillary carcinoma of the breast: An analysis from the National cancer data base

Abstract

Abstract Purpose/Objectives: Invasive micropapillary carcinoma (IMPC) is an uncommon variant of breast cancer, accounting for <2% of all cases. Previous studies demonstrated that this subtype often presents with hormone receptor (HR) positive disease, resulting in survival outcomes similar to invasive ductal carcinoma. However, many of these studies were conducted prior to the availability of HER2 testing. In this study, we aim to determine the impact of molecular marker status (including HER2 status) on survival outcomes of invasive micropapillary carcinoma. Materials/Methods: The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven IMPC diagnosed from 2007-2012. Only patients with known estrogen receptor (ER) status, progesterone receptor (PR) status and HER2 status were included in the analysis. Cox multivariate regression was used to determine prognostic factors. Results: Overall, 865 patients met inclusion criteria. The median follow-up was 2.5 years. Out of all patients, 651 (75.3%) had HR+, HER2 negative disease, 128 (14.8%) had HR+, HER2+ disease, 41 (4.7%) had HR negative, HER2+ disease, and 45 (5.2%) had triple negative disease. Patients with triple negative disease were more likely to have poorly differentiated/undifferentiated histology (66.7%), lymphovascular invasion (73.3%), stage 3 disease (37.8%), undergone mastectomy (68.9%), and positive surgical margins (15.6%). On Cox multivariate regression, those with triple negative disease had worse overall survival (hazard ratio 7.28, P<0.001). Other prognostic factors associated with worse overall survival included African American descent (hazard ratio 2.24, P=0.018), comorbidity score of 1 (hazard ratio 2.50, P=0.011), comorbidity score ≥2 (hazard ratio 3.27, P=0.06), and ≥3 positive lymph nodes (hazard ratio 3.23, P=0.007). Conclusions: Similar to invasive ductal carcinoma, triple negative disease in invasive micropapillary carcinoma results in worse survival outcomes. This is the largest and first study to characterize molecular status (including HER2 status) in IMPC patients, as well as its impact on survival outcomes. Citation Format: Lewis GD, Xing Y, Patel T, Schwartz M, Rodriguez AA, Chen AC, Farach A, Hatch SS, Butler EB, Chang JC, Teh BS. The impact of molecular status on survival outcomes for invasive micropapillary carcinoma of the breast: An analysis from the National cancer data base [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-09-06.