XRCC1 and cancer: They also reported that the XRCC1 399Gln/399Gln genotype was associated with a decreased cancer risk among heavy smokers (OR = 0.71, 95% CI, 0.51–0.99), but an increased cancer risk among light smokers (OR = 1.38, 95% CI, 0.99 – 1.94) [41].