Factors contributing to the prevalence of prostate cancer in rural Saskatchewan : the Saskatchewan Rural Health Study

Abstract

Prostate cancer is the most commonly diagnosed cancer in Canadian males, and is the third most common cause of cancer related deaths with decreasing mortality in men. Previous studies have suggested that an increased risk of prostate cancer among men may be associated with rural environment. The etiology of prostate cancer is not precisely known among men in rural Saskatchewan. We investigated the prevalence of prostate cancer and the putative relationship between rural exposures (occupational i.e. farming and environmental), personal smoking history, family history of cancer and prostate cancer. A baseline mail out survey was conducted in 2010-2011 of 11,982 households located in four geographic regions (South West, South East, North West, and North East) of Saskatchewan, Canada. Completed questionnaires were obtained from 4,624 households (8,261 individuals). The questionnaires collected information on individual (demographic factors, exposure to pesticides including insecticides, herbicides and fungicides) and contextual (household characteristics such as income, smoking) determinants from a rural population. In total 2,938 males (114 prostate cancer cases) were included for this analysis who were older than 45 years. Logistic regression analysis was used to analyze the relationship between independent variables and prostate cancer. Among prostate cancer cases, 46% of men lived on farms of rural Saskatchewan. The age standardized prevalence of prostate cancer was 3.32% (3.81% (n=52) and 2.95% (n=61) among farm and non-farm resident men). Farming job and farming duration did not have a statistically significant association with prostate cancer. A trend was observed for men who had work place exposure to insecticides and fungicides collectively and radiation to have an increased risk in comparison to men without these exposures. Personal smoking history, history of smoking pack years and family history of cancer modified the relationship between residence and prostate cancer. Age of an individual (≥ 65 years) was the strongest and most consistent risk factor of prostate cancer. Other factors such as marital status, household income adequacy, history of cardiovascular disease may also be associated with prostate cancer. The results may help research professionals by directing the focus of their research towards rural population examining prostate cancer.