Multivitamin uptake may increase prostate cancer risk: analysis of the New South Wales 45 and up study

Abstract

Introduction & Background: Multivitamins marketed specifically for men's health needs, including prostate health are common. Many such multivitamins contain vitamin E, zinc and selenium, which are promoted as improving prostate health. Reported rates of multivitamin use in the Australian adult community are as high as 49%. Evidence from the SELECT study demonstrates increased risk of prostate cancer in men who regularly take vitamin E supplements. The National Institutes of Health (NIH) AARP Diet and Health Study, a large retrospective cohort study of US adults, found an increased risk of advanced and fatal prostate cancer in men regularly consuming multivitamins. Our aim is to determine if Australian men taking supplements and vitamins have an increased risk of diagnosis of prostate cancer. Methods: A prospective study of the New South Wales male population participating in the Sax Institute's 45 and Up Study, a large cohort study of approximately 123 000 New South Wales men aged 45 years and above. After applying exclusion criteria (mostly men with prevalent prostate cancer), our study cohort consisted of 94,680 men. Participants completed a survey at baseline and their records were subsequently linked by the CHeReL to hospital admissions, the Cancer Registry for cancer registrations up to December 2010 and to Medicare claims data supplied by the Department of Human Services. Comparison of risk of diagnosis of prostate cancer in men who reported that they regularly took multivitamins and supplements was compared to men who did not. Adjusted hazard ratios for PC diagnosis was estimated using Cox regression. Results: In this New South Wales cohort 94 680 men were identified as at risk of diagnosis at baseline. Almost half (45%) reported use of supplements or multivitamins. Subsequently, 2097 men were diagnosed with prostate cancer up to 4 years after baseline interview. After adjusting for socio-economic factors, number of doctors visits, PSA testing behaviour and comorbidity we found a 9% increased risk of developing prostate cancer in men taking vitamins and supplements (HR 1.09, 95% CI = 1.00-1.19, p= 0.06), which is approaching statistical significance. This is consistent with data from the SELECT study. Further follow up of this cohort, both in terms of length of time and with stratification by disease stage will be undertaken. Conclusion: The use of multivitamins and supplements within the community is widespread, many of which are marketed towards men with the aim of improving prostate health. Given these findings, men need to be counselled regarding the efficacy and risks associated with such treatments.