Abstract 1183: Race, copy number variation, and local hog concentration in breast cancer mortality
Authors: Byun Jung S. , Lee Sean , Yun Sijung , Perez-Stable Eliseo J. , Napoles Anna M. , Strickland Paul , Gardner Kevin L. 
Published: September 2020

Purpose of study: Female breast cancer is the second leading cause of cancer death in U.S. women, and the incidence of new breast cancer cases continues to increase. Despite slightly lower breast cancer incidence rates among African American (AA) compared to European American (EA) women in the U.S., AA women experience significantly higher breast cancer mortality. To better understand the extent to which environmental and genetic factors might help explain higher mortality rates among AA women, we examined the association between a measure of exposure to chemical pollutants and genomic profiling with breast cancer mortality among women with breast cancer in North Carolina.

Procedures: Using a molecular epidemiologic approach, we examined the association of county hog concentration (a marker of environmental exposure to chemical pollutants) and genomic variations identified via targeted exome sequencing with age-adjusted breast cancer mortality rates among 146 women in North Carolina, stratified by race (AA vs. EA). The odds of breast cancer-specific mortality were estimated as a function of county hog concentration quintiles.

Results: Overall, breast cancer mortality among AA women was higher than among EA women (OR=1.4, p&lt;0.0001). Although there was no effect of hog concentration on breast cancer mortality of EA women, there was an increase in deaths from breast cancer in African American women in the highest quintile of hog concentration (OR=1.18, p=0.03), compared to the lower quintiles. In the lowest quintile of hog concentration, breast cancer mortality remained higher among AA versus EA women (OR=1.38, p=0.0002). This suggests that along with environmental factors, biological factors also contribute to disparities. Next, we performed targeted exome sequencing of breast cancer samples collected from a cohort in eastern North Carolina. AA breast cancer samples showed a high frequency of CNVs (copy number variations) of COL11A2, COL12A1, CYP21A2, LYRM2, COL9A1, DNAH11, and DST. EA breast cancer samples showed a high frequency of CNVs of PRG4, PLB1, CHRM5, OCA2, HMCN1, and MUC5B. Among these, HMCN1, MUC5B (among EA), and COL12A1, DNAH11, DST (among AA) were genes with significantly high CNVs identified from The Cancer Genome Atlas.

Conclusions: Our findings suggest that living in a county with a high concentration of hogs may increase breast cancer mortality risk among AA women, and the high frequency of CNVs varies by race; both CNV and county hog concentration may contribute to racial disparities in breast cancer mortality among AA and EA women in North Carolina.

Citation Format: Jung S. Byun, Sean Lee, Sijung Yun, Eliseo J. Perez-Stable, Anna M. Napoles, Paul Strickland, Kevin L. Gardner. Race, copy number variation, and local hog concentration in breast cancer mortality [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1183.