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

Abstract

Epidemiologic studies examining associations of circulating concentrations of retinol and carotenoids with prostate cancer risk have been mixed. This study examined associations with serum retinol and carotenoids in a case‐control study nested within the Prostate Cancer Prevention Trial (n = 1752 controls, 1687 cases). Presence or absence of cancer was determined by prostate biopsy, recommended during the trial due to elevated prostate specific antigen (PSA) or abnormal digital rectal examination (DRE), and offered to all men at trial end. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusting for age, race, BMI, family history of prostate cancer, and serum cholesterol. In the placebo arm, men in the highest quartile of serum retinol had a 30% (OR (95% CI): 1.30 (1.00, 1.68), P‐trend = 0.04) and 74% (OR (95% CI): 1.74 (1.14, 2.68), P‐trend = 0.02) increased odds of total and high‐grade prostate cancer, respectively, relative to those in the lowest. The highest quartile of serum α‐carotene was associated with a 32% (OR (95% CI): 1.32 (1.01, 1.73), P‐trend = 0.03) increased odds of total prostate cancer, relative to the lowest. Associations with retinol were strongest in men who used vitamin A supplements, or who were diagnosed due to abnormal PSA or DRE. There were no associations with serum retinol and α‐carotene in the finasteride arm, or with β‐carotene and β‐cryptoxanthan in either treatment arm. This study was supported by the National Cancer Institute: P01 CA108964, U01 CA37429.