Significant Reduction in Breast Cancer Risk for Japanese Women with Interleukin 1B -31 CT/TT Relative to CC Genotype

Abstract

OBJECTIVE: The present case-control study aimed to examine the associations between breast cancer risk and three functional polymorphisms (Interleukin (IL) -1A C-889T, IL-1B C-31T and IL-1RN 86-bp variable number tandem repeat) related to expression of IL-1beta, which combines estrogen receptor. METHODS: Cases were 231 patients with breast cancer who had been diagnosed 1 month to 6 years before their enrollment in 1999-2000 at Aichi Cancer Center Hospital. Controls were 186 non-cancer outpatients recruited during the same period at the digestive tract, breast surgery and gynecology clinics. RESULTS: There were no differences in the genotype distributions of the IL-1A and IL-1RN polymorphisms, but individuals harboring a IL-1B C-31T T allele (high expression allele) were less frequent among cases (74.3%) than among controls (84.9%). The age-adjusted odds ratio (OR) relative to CC genotype was 0.52 (95% confidence interval, 0.30-0.88) for CT genotype, 0.58 (0.32-1.02) for TT genotype and 0.54 (0.33-0.90) for CT/TT genotype. Subgroup analysis showed that the preventive effect was significantly stronger for postmenopausal women than for premenopausal women (interaction 0.30, 0.11-0.84). CONCLUSIONS: Although this is the first report on the association between breast cancer risk and IL-1B C-31T, the observed association seems plausible in a biological sense.