Serum Retinol and Carotenoid Concentrations and Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial.

BACKGROUND - Findings from epidemiologic studies examining associations of serum retinol and carotenoids with prostate cancer risk have been inconsistent. This case-control study nested in the Prostate Cancer Prevention Trial evaluated associations of serum retinol and carotenoids with total, low- and high-grade prostate cancer risk in a highly-screened study population.

METHODS - We used logistic regression adjusting for age, family history of prostate cancer, race, BMI and serum cholesterol to estimate odds ratios (OR) and 95% confidence intervals (CI) of prostate cancer by quartiles of serum retinol and carotenoids, separately in the placebo (975 cases/1009 frequency-matched controls) and finasteride (708 cases/743 frequency-matched controls) arms of the trial.

RESULTS - Serum retinol concentrations were associated with increased risk of total prostate cancer [OR (95% CI) comparing the highest quartile of serum retinol to the lowest: 1.30 (1.00, 1.68)] and high-grade prostate cancer [OR (95% CI): 1.74 (1.14, 2.68)] in the placebo arm of the trial only. Also in the placebo arm, there was a moderate positive association of α-carotene with risk of total prostate cancer [OR (95% CI): 1.32 (1.01, 1.73)]. None of the other carotenoids was associated with prostate cancer risk in the placebo arm. No associations were observed for retinol and carotenoids in the finasteride arm.

CONCLUSIONS - In the placebo arm of this prospective study, high serum retinol and α-carotene concentrations were associated with increased risk of total and high-grade prostate cancers.

IMPACT - Men with higher levels of serum retinol and α-carotene may be at increased risk for prostate cancer.

Cancer Epidemiol Biomarkers Prev. 2015 Aug 12. pii: cebp.0394.2015. [Epub ahead of print]

Nash SH1, Till C2, Song X3, Lucia MS4, Parnes HL5, Thompson IM Jr6, Lippman SM7, Platz EA8, Schenk J9.

1 Cancer Prevention Fellowship Program, National Cancer Institute.
2 Fred Hutchinson Cancer Research Center.
3 Cancer Prevention Program, Fred Hutchinson Cancer Research Center.
4 Pathology, University of Colorado.
5 DCP, NCI.
6 Cancer Therapy and Research Center, The University of Texas Health Science Center at San Antonio.
7 University of California, San Diego, Moores Cancer Center.
8 Epidemiology, Johns Hopkins University School of Public Health.
9 Fred Hutchinson Cancer Research Center