Abstract 4153: Global African ancestry is not associated with lung cancer survival

Lung cancer is the leading cause of cancer-related mortality among men and women in the United States, accounting for 27% of all cancer-related deaths. Blacks experience poorer 5-year survival compared to whites. We hypothesized that individuals with higher global African ancestry have poorer survival compared to individuals with lower global African ancestry. We identified incident non-small cell lung cancer cases in the Southern Community Cohort Study (SCCS), a prospective study of low-income adults recruited from across the Southeast region of the United States. Individuals who donated a biospecimen were genotyped using the Illumina Human Exome BeadChip, which contains a panel of ancestry informative markers (AIMs). After standard quality control, 398 individuals (262 self-reported black and 134 self-reported white) remained for analysis. Global ancestry was estimated from 2,604 AIMs using the software program ADMIXTURE. Self-reported blacks had a median global African ancestry of 88.12%, while the median global African ancestry in self-reported whites was less than 0.01%. We estimated hazard ratios and 95% confidence intervals using Cox proportional hazard models adjusted for age, sex, body mass index (BMI), cigarettes per day, disease stage, treatment, insurance coverage, family history of lung cancer and recruitment site. BMI, age, cigarettes per day and global African ancestry were modeled using restricted cubic splines. We estimated time dependent area under the curve (AUC) for our main effects model and a main effects model with interactions, both with and without genetic ancestry. We found that the main effects model had an average AUC of 0.81. When global African ancestry was excluded, the AUC was minimally reduced to 0.80. When interactions were added to the main effects model, the AUC increased to 0.88. Removal of global ancestry from the interactions model reduced the AUC to 0.84. In the main effects model, the two most predictive variables were stage and treatment with X2 values of 36.13 (degrees of freedom, df=2) and 15.47 (df=4), respectively. While we conclude that global African ancestry has little effect on overall survival, a relationship between global African ancestry and stage or treatment remains to be investigated. Citation Format: Carissa C. Iverson, Sarah Fletcher, Jeffery Blume, Holli Dilks, Heidi Chen, Stephen A. Deppen, William S. Bush, Dana C. Crawford, William J. Blot, Eric L. Grogan, Melinda C. Aldrich. Global African ance