Elevated levels of insulin-like growth factor I (IGF-I) may be associated with an increased risk of prostate cancer in Latino men, according to researchers.

Jasmeet K. Gill, MD, of California State University in Fullerton, analyzed biomarkers of prostate cancer risk among men in the Multiethnic Cohort Study of African-Americans, Caucasians, Japanese-Americans, Latinos, and Native Hawaiians.

The researchers compared 467 men who developed prostate cancer and 934 cancer-free controls with respect to prediagnostic serum levels of testosterone, dihydrotestosterone, IGF-I, and IGF-II, IGF-binding protein 1 (IGFBP-1), and IGFBP-3. Overall, the concentrations of these biomarkers were not associated with prostate cancer risk, the authors reported in The Prostate (published online ahead of print).

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When the investigators analyzed results by ethnic group, however, they found that Latino men in the second tertile of IGF-I level had a significant 3.7 times increased risk of prostate cancer compared with men in the first tertile; those in the third tertile had a significant threefold increased risk.

In addition, the study revealed a significant inverse association between IGF-I levels and prostate cancer risk in African-American men. Those in the third tertile of IGF-I concentration had a 46% reduced risk of prostate cancer compared with men in the first tertile.

Dr. Gill’s group noted that Latino men had the lowest mean IGF-I levels among the ethnic groups, “which is contrary to the belief the high IGF-I levels should be related to increased risk of prostate cancer because IGF-I’s cell proliferative and anti-apoptotic effects.”