Abstract LB-274: Mode of breast cancer detection: Do markers of tumor aggressiveness predict which tumors are “missed” at screening

Abstract

Abstract Screening mammography reduces breast cancer stage at diagnosis by detecting it early before symptoms develop. Nonetheless, a breast cancer can arise as a lump despite a recent prior negative screen (“missed detection”). In the Breast Cancer Care in Chicago study, Non-Hispanic (nH) Black and Hispanic women were more likely than their nH White counterparts to report a missed detection despite a recent prior screening mammogram. We examined whether breast cancer subtype and immunohistochemical (IHC) markers of tumor aggressiveness predicted missed detection and whether they could explain racial/ethnic disparities in missed detection, in a subsample of 198 patients with a recent prior screening mammogram (63 Non-Hispanic White, 78 Hispanic and 57 African American). Missed detection was defined as symptomatic awareness despite a negative screen in the prior 24 months. IHC analyses were conducted for estrogen receptor (ER), progesterone receptor (PR), HER2, EGFR and CK5/6, Ki67 and p53 expression. Breast cancers were classified as Luminal A (ER+/PR+/HER2-), Luminal B (ER+/PR+/HER2+), HER2 enriched (ER-/PR-/HER2+), and triple negative (TN) (ER-/PR-/HER2-). Missed detection was highest for more aggressive TN and HER2 enriched subtypes (61% and 60%) and lowest for luminal A and B tumors (37% and 38%). Greater Ki67, EGFR and p53 expression were each associated with missed detection (p<0.02 for all), while PR and CK5/6 were marginally associated with missed detection. Before accounting for tumor characteristics, missed detection was twice as likely for minority than for nH white patients (47% vs. 24%, p=0.002); and the disparity in missed detected remained nearly the same after adjustment for tumor aggressiveness markers (47% vs. 27%, p=0.013) In this multi-ethnic sample of breast cancer patients, markers of tumor aggressiveness were strongly associated with missed detection at screening but they did not explain racial/ethnic disparities in missed detection. Citation Format: Abeer Mostafa Mahmoud, Virgilia Macias, Jacob K. Kresovich, Andre Kajdacsy-Balla, Elizabeth L. Wiley, Garth H. Rauscher. Mode of breast cancer detection: Do markers of tumor aggressiveness predict which tumors are “missed” at screening. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-274. doi:10.1158/1538-7445.AM2014-LB-274