Abstract C73: A relationship between mast cells and the racial disparity of prostate cancer

Abstract

Abstract Prostate cancer afflicts African American men to a greater degree than European American men, with a 60% greater incidence and 2-3 times greater mortality. In addition, studies have shown that the incidence rate of distant metastasis is 4 times greater in African American men than in European American men, consistent with the notion that prostate cancer is more aggressive in African Americans. Of interest, African American men are also significantly more likely to present with inflammation in benign prostate biopsies, and studies have shown higher expression of a number of inflammatory markers in prostate cancer tissue from African Americans compared to European Americans. One immune cell type of particular interest in the context of prostate cancer are mast cells, which have the potential to play a number of roles in cancer, and have also been shown to increase in number in prostate cancer versus benign regions of the prostate. In the present study, immunohistochemistry (IHC) was used to directly visualize and localize mast cells in the prostate microenvironment of African American and European American men in a tissue microarray (TMA) containing tumor and benign tissues from 75 African American and 75 European American prostate cancer patients matched on tumor grade and stage. Automated counting of mast cell numbers as well as the calculation of mast cell-to-epithelial ratio (MC/Ep) and mast cell numbers per total tissue area (density) was aided by novel digital image analysis using a software framework integrating whole slide imaging, virtual microscopy, and ImageJ based analysis algorithms. Key results to date include the finding that mast cell density in prostate tumor tissues of African American men is significantly lower than that of Caucasian Americans (p < 0.0001). This same trend was observed for total mast cell numbers and MC/Ep (p=0.001). These results suggest the intriguing possibility that a decrease in tumor-infiltrating mast cells may contribute to the racial disparity observed in association with prostate cancer and additional studies are underway to determine the biological function of mast cells in the prostate tumor microenvironment. Citation Format: Heidi A. Hempel, Ibrahim Kulac, Nathan S. Cuka, Toby C. Cornish, Angelo M. De Marzo, Karen S. Sfanos. A relationship between mast cells and the racial disparity of prostate cancer. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C73.