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 ancestry is not associated with lung cancer survival. [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 4153. doi:10.1158/1538-7445.AM2014-4153

Pleiotropic associations of risk variants identified for other cancers with lung cancer risk: the PAGE and TRICL consortia

BACKGROUND

Genome-wide association studies have identified hundreds of genetic variants associated with specific cancers. A few of these risk regions have been associated with more than one cancer site; however, a systematic evaluation of the associations between risk variants for other cancers and lung cancer risk has yet to be performed.

METHODS

We included 18023 patients with lung cancer and 60543 control subjects from two consortia, Population Architecture using Genomics and Epidemiology (PAGE) and Transdisciplinary Research in Cancer of the Lung (TRICL). We examined 165 single-nucleotide polymorphisms (SNPs) that were previously associated with at least one of 16 non-lung cancer sites. Study-specific logistic regression results underwent meta-analysis, and associations were also examined by race/ethnicity, histological cell type, sex, and smoking status. A Bonferroni-corrected P value of 2.5×10(-5) was used to assign statistical significance.

RESULTS

The breast cancer SNP LSP1 rs3817198 was associated with an increased risk of lung cancer (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.05 to 1.14; P = 2.8×10(-6)). This association was strongest for women with adenocarcinoma (P = 1.2×10(-4)) and not statistically significant in men (P = .14) with this cell type (P het by sex = .10). Two glioma risk variants, TERT rs2853676 and CDKN2BAS1 rs4977756, which are located in regions previously associated with lung cancer, were associated with increased risk of adenocarcinoma (OR = 1.16; 95% CI = 1.10 to 1.22; P = 1.1×10(-8)) and squamous cell carcinoma (OR = 1.13; CI = 1.07 to 1.19; P = 2.5×10(-5)), respectively.

CONCLUSIONS

Our findings demonstrate a novel pleiotropic association between the breast cancer LSP1 risk region marked by variant rs3817198 and lung cancer risk.