Quantile–quantile plots of 42 interaction P values for seven SNPs under investigation. Quantile–quantile plots of 42 interaction P values for seven SNPs under investigation. P values were derived from interaction models in which SNP genotype was modeled as a continuous variable with values of 0/1/2 in A. A randomly selected set of seven SNPs from the BEAGESS study were also plotted for comparison in B for the trend interaction test. P values from the interaction test with SNP genotypes modeled as 0/1 were displayed in C, along with the random set of seven SNPs in D. James Y. Dai et al. Cancer Epidemiol Biomarkers Prev 2015;24:1739-1747 ©2015 by American Association for Cancer Research