Background: Both prostate cancer and diabetes mellitus are common diseases in African-American men. High insulin levels and insulin resistance have been implicated in prostate cancer development, which has prompted a recent investigation of a possible role for germline variation in the insulin gene (INS) and prostate cancer risk.
Methods: Four hundred sixty-six African-American men with and without prostate cancer from the Flint Men's Health Study were typed for the INS Pst1 genotype using restriction digest and direct sequencing. An association between the Pst1 genotype and prostate cancer was examined using crude and age-adjusted logistic regression models.
Results: African-American men who were homozygous for the INS PstI CC genotype were 1.59 times more likely to be diagnosed with prostate cancer compared to men with the TT or TC genotypes (95% CI = 0.93-2.72). The association appeared stronger among diabetics compared to non-diabetics; however this observation was not statistically significant.
Conclusions: Our study, taken together with the report of Ho et al., suggests that the INS Pst1 CC genotype is associated with prostate cancer risk in African-American men. Germline variation in the INS gene should be more fully explored in multiethnic studies to elucidate the molecular variant(s) associated with prostate carcinogenesis.