For rectal cancer four SNPs in TXNRD1, TXNRD2, and TXNRD3 interacted with aspirin/NSAID use and two SNPs in TXNRD1 interacted with cigarette smoking; the step-down Bonferroni correction was greater than 0.15 for all of these associationsFor rectal cancer and aspirin, the greatest effect of the genes appeared to be among non-NSAID users while among those who smoked cigarettes the variant allele appeared to reduce the risk of rectal cancer associated with smoking. The gene discussed is TXNRD3; the disease is rectal cancer.