Interaction of dietary antioxidant intake and selected DNA repair polymorphisms and breast cancer risk in Poland
High intake of fruits and vegetables has been shown to decrease breast cancer. Impaired DNA repair capacity may adversely affect cancer risk among women deficient for protective factors found in fruits and vegetables. We evaluated intake of fruit, vegetable, antioxidants and variants of selected SNPs in XRCC1, XRCC2, and XRCC3 in relation to breast cancer risk.
METHODS:
Data were derived from population-based case-control study (2,386 cases, 2,502 controls) conducted in Poland. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).
RESULTS:
Breast cancer risk was higher for women with low intake of fruit and juices (OR=1.31, 95%CI=1.08-1.58 for 1st vs. 4th quartile; ptrend=0.003), α-carotene (OR=1.32, 95%CI=1.10-1.58), β-carotene (OR=1.30; 95%CI=1.09-1.56; ptrend=0.03), and lycopene (OR=1.24; 95%CI=1.04-1.48; ptrend=0.02). No association of breast cancer risk with intake of vegetables, folate, and vitamin C was observed. Variants in XRCC1 Ex10-4, XRCC2 Ex3+442, as well as in XRCC3 Ex2+2 were not independently associated with breast cancer risk. Polymorphisms in XRCC3 Ex8-53 (OR=1.33, 95%CI=1.1-1.6), and XRCC3 IVS7-14 (OR=0.80, 95%CI=0.66-0.99) were weakly associated with breast cancer risk. Most antioxidant-related associations were limited to carriers of the XRCC1-399 Arg/Arg genotype (p for interaction 0.02-0.09). Significant increase in risk was observed for women carrying XRCC2 Ex3+442 GG genotype with low intake of fruits and juices, and carotenoids. Similarly, increased risk associated with low intake of total carotenoids, α- and β-carotene, tented to be greater for carriers of XRCC3-241 Met/Met. Breast cancer risks among women with two copies of variant alleles at the XRCC3-241 who were low in α- and β-carotene were 1.93 (95%CI=1.30-2.86) and 1.95 (95%CI=1.32-2.88), respectively. Borderline associations for Met/Met carriers were found for fruits, folate, vitamin C, lycopene, cryptoxanthin.
CONCLUSIONS:
We provide further support that differences in DNA repair capacity may modulate the effect of dietary antioxidant intake on breast cancer risk.