Postscreening follow-up of the Finnish Prostate Cancer Screening Trial on putative prostate cancer risk factors: vitamin and mineral use, male pattern baldness, pubertal development and non-steroidal anti-inflammatory drug use.
Objective The etiology of prostate cancer (PCa) is still unclear. This study aimed to investigate the association between PCa risk and the indicators of endogenous androgen production at puberty, male pattern baldness, over-the-counter use of non-steroidal anti-inflammatory drugs and vitamin supplement use. Materials and methods Participants in the third round of the Finnish Prostate Cancer Screening Trial were sent a survey on possible PCa risk factors and 11,795 out of 12,740 (93%) men returned the questionnaire. PCa cases were identified from the Finnish Cancer Registry. Results During the median follow-up of 6.6 years, 757 PCa cases were diagnosed and 21 men died from PCa. Compared to earlier onset, puberty onset after 15 years of age was associated with a borderline significant decrease in PCa risk [hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.75-1.00] but not with PCa mortality. Weekly use of ibuprofen was associated with an increased risk of PCa overall (HR 1.43, 95% CI 1.08-1.91) and with metastatic PCa (HR 1.49, 95% CI 1.12-1.99) compared to less frequent use. No statistically significant association was found between vitamin use and PCa. Conclusions This study suggests that the timing of initiation of endogenous androgen production at puberty may have importance for later PCa development. Current use of over-the-counter ibuprofen is associated with an increased risk of PCa. There was no evidence of any protective effects of vitamin use on PCa risk.