Haplotype CA in XRCC1 was associated with a statistically significant increase in PC risk (OR = 1.32, CI = 1.01–1.71; P = 0.042) as compared with the most common haplotype, CG, in XRCC1. As shown in Table 4, we defined haplotype CA in XRCC1 as a risk haplotype and analyzed the potential interactions between risk haplotype and known PC risk factors (smoking, alcohol consumption, overweight, diabetes mellitus, and family history of PC). Here, XRCC1 is linked to diabetes mellitus.