Abstract P4-05-07: Molecular profiles of screen detected breast cancers: Final results of Turkish Bahcesehir breast cancer screening project

Abstract

Abstract Objectives: Turkish Bahcesehir Breast Cancer Screening Project is a 10-year organized population based screening program carried out in one of the largest counties of Istanbul, Turkey. The aim of our study is to examine the biological features of screen detected breast cancers detected during the initial 4-year study period as an interim analysis. Study Design and Methods: Between January 2009 and May 2013, a total of 6298 women with ages 40–69 years were recruited in this prospective study. Two-view mammographies were obtained by 2-year intervals, and classified according to Breast Imaging Reporting and Data System of the American College of Radiology (ACR). Clinicopathological and biological tumor characteristics were analysed for those diagnosed with breast cancer. Tumors were stained for estrogen (ER) and progesterone receptors (PR), HER2-neu and Ki-67 by immunohistochemistry. Results: A total of 57 breast cancers (%0.9) were detected during the study period. The median age was 50 (40-70). The majority of patients (72%) were stage 0 or 1, whereas 28 patients (49%) were <50 age. Of 57 tumors, 45 (79%) were invasive cancers and 12 (21%) were ductal carcinoma in situ. Forty-eight patients (86%) underwent breast conservation, whereas 37 patients (65%) had sentinel lymph node biopsy only as axillary procedure. Of 45 invasive cancers, 31 (69%) were ductal carcinoma and 8 (18%) were pure lobular cacinoma. Among 45 invasive cancers stained for ER, PR, HER2-neu and Ki67, the majority of them (91%) were ER or PR receptor positive, whereas 11% were HER2-neu positive and 58% had low Ki67 levels (≤15). As molecular subtypes, the majority of them were found to be either luminal A (57%) or luminal B type (34%), whereas other nonluminal HER2 (4%) and triple negative cancers (5%) were less frequently detected. Conclusions: Our findings suggest that the majority of screen-detected breast cancers exhibit either luminal A or B subtype. However, more aggressive subtypes such as nonluminal HER2-neu or triple negative cancer are less likely to be detected by mammographic screening programs, requiring other preventive strategies. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-05-07.