Polymorphisms in hOGG1 and XRCC1 and Risk of Prostate Cancer: Effects Modified by Plasma Antioxidants

Background—Accumulating evidence indicates that oxidative stress plays a role in prostate carcinogenesis. This study thus investigated whether polymorphisms in genes involved in the repair of oxidative DNA damage modulate and/or interact with antioxidants to influence prostate cancer risk in a population-based case-control study in Central Arkansas. Methods—Cases (n=193) were men, ages 40–80 years, diagnosed with prostate cancer in three major hospitals in 1998–2003, and controls (n=197) were matched to cases by age, race, and county of residence. Results—After adjustment for confounders, subjects who were heterozygous or homozygous for the variant allele of the hOGG1 Ser326Cys polymorphism appeared to experience a lower risk of prostate cancer than those who were homozygous for the wild-type allele [OR (95%CI): 0.72 (0.46– 1.10)]. Conversely, a significant increased risk was observed for individuals who carried one or two copies of the variant allele of the XRCC1 Arg399Gln polymorphism, compared with those who only harbored the wild-type allele [OR (95%CI): 1.56 (1.01–2.45)]. The above associations were generally more pronounced among subjects with low plasma carotenoids or α-tocopherol (cryptoxanthin (<73 μg/l), possession of at least one copy of the XRCC1 399Gln allele conferred an over two-fold elevated risk [OR (95%CI): 2.64 (1.40– 5.07)]. Conclusions—Our study offers preliminary but intriguing data suggesting that variability in the capacity of repairing oxidative DNA damage influences susceptibility to prostate cancer and that these effects are modified by antioxidants.