Purpose: Prostate cancer is the most common cancer among men and accounts for most cancer related deaths in Sweden today. To find or confirm exogenous risk factors for prostate cancer a population based case-control study was performed.
Materials and methods: By linking the Swedish Cancer Registry with the Swedish Twin Registry 406 cases of prostate cancer were selected from the twin register. As controls 1,218 men without prostate cancer were randomly selected from the same register. The selection procedure ensured that no cases or controls were related to each other. Questionnaire concerning height, weight, dietary habits, and alcohol and tobacco consumption were mailed in 1967 and 1970 to members in the twin register and the collected information was used in this study.
Results: There was a positive trend for prostate cancer risk seen for total food consumption to (p < 0.001) with an odds ratio of 2.22 (95% confidence interval 1.23 to 3.99) for those who consumed somewhat more and 3.89 (1.09 to 13.96) for those who consumed much more than people in general. An increased trend was also seen for body mass index (BMI) (p = 0.015), with an odds ratio of 1.44 (0.98 to 2.11) for 26 to 29 kg./m.2 and 1.80 (1.07 to 3.04) for BMI greater than 29 kg./m.2 compared with BMI less than 23 kg./m.2. Total food consumption and BMI remained independent risk factors in a multivariate analysis. All specific food items studied, as well as tobacco and alcohol consumption, were unrelated to prostate cancer risk.
Conclusions: This study suggests that high BMI and total food consumption are independent risk factors for prostate cancer and that dietary habits are important in the development of this tumor. It is also unlikely that neither tobacco nor alcohol use substantially changes the risk of prostate cancer.