Plasma prolactin and prostate cancer risk: A prospective study

Prolactin, a pituitary peptide hormone with multiple effects, stimulates pr ostate growth in experimental models. In humans, prolactin receptors are pr esent in the prostate and are particularly abundant in pre-cancerous lesion s. This suggests that prolactin could also be involved in the development o f prostate cancer. In this study, we tested the hypothesis that elevated le vels of circulating prolactin are associated with an increase in prostate c ancer risk. We conducted a case-control study nested within the Northern Sw eden Health and Disease Cohort using plasma samples collected from 29,560 m en at a health survey. We measured prolactin in plasma from 144 men who had a diagnosis of prostate cancer after a median follow-up time of 4 years af ter health survey and from 289 controls matched for age and date of recruit ment. Risk was not associated with plasma prolactin levels in univariate re gression analysis. Odds ratios of prostate cancer for increasing quartiles of prolactin were 1.0, 0.92 (95% CI 0.51-1.65), 0.82 (0.45-1.51) and 0.85 ( 0.49-1.47), Relative risk estimates remained unchanged after adjustments fo r height and weight or for plasma levels of testosterone, sex hormone-bindi ng globulin, IGF-I and IGF-binding protein-3. Elevated circulating levels o f prolactin were not related to an increase in prostate cancer risk, indica ting that high circulating prolactin is not associated with development of prostate cancer. (C) 2001 Wiley-Liss, Inc.