Clinicopathological features and prognosis of pregnancy associated breast cancer - a matched case control study

Pregnancy Associated Breast Cancer (PABC) manifests during pregnancy or within a year following delivery. We sought to investigate differences in management, outcome, clinical, histopathology and immunohistochemistry (IHC) characteristics of PABC and matched controls in a retrospective case control study. PABC and control patients were selected from breast cancer cases of women ≤45 years, diagnosed in the 2nd Department of Pathology, Semmelweis University, Budapest, Hungary between 1998 and 2012. Histopathology information on tumor type, grade, size, T, N, lympho-vascular invasion (LVI), Nottingham Prognostic Index (NPI), associated in situ lesions and IHC charcteristics: ER, PgR, HER2, Ki67, p53 were recorded, IHC-based subtype was assessed, clinical, management and outcome data were analysed. Thirty-one breast cancer cases were pregnancy related. Clinical management data did not differ in cases and controls. Histopathology of disease at presentation was not significantly different, but NPI assessed the PABC group as having poor, whereas controls as having intermediate prognosis. Associated in situ lesion was more often high grade Extensive Intraductal Carcinoma Component (EIC) in PABC. Triple negative and LuminalB prol tumors predominated in PABC. Disease-free and overall survival was inferior compared to controls. PABC patients with LuminalB prol and Triple negative tumors had inferior outcomes. On multivariate analysis inferior prognosis of PABC was associated with pregnancy. Our study has demonstrated inferior outcome of PABC. Difference in tumor biology is reflected by the predominance of triple negative and LuminalB tumors in PABC. The strength of the study is the analysis of complete pathology and IHC data.