A case control study of occupational exposures and the risk of prostate cancer
The purpose of this research project was to investigate the occupational exposures of participants in a case control study of prostate cancer. By age 60 years over 50% of men will have cancerous lesions in their prostate. It has been suggested that at age 115 years, all men would have prostate cancer. Although most men will develop some form of prostate cancer only a small proportion die from it. The important determination by doctors with their patients is to identify which prostate cancers are low to moderate grade and can be treated or ignored and which are high grade and need to be removed immediately to prolong life. DATA COLLECTION AND ANALYSIS The occupational literature suggests and supports the contention that certain agents in the workplace are associated with increased risk of prostate cancer but these observations require further corroboration. Data on self-reported occupational histories were available from an Australian case control study conducted between 1994 and 1998. The data were analysed using the Finnish Job Exposure Matrix (FINJEM). The researcher coded the occupational work histories for each of the 1,436 cases and 1,349 controls that were frequency matched on age to each to the cases, and examined the level of exposure of occupational groups to the risk and severity of prostate cancer. The level of exposure of the occupational groups in relation to the prostate cancer risk was examined for 23 variables related to chemical, ergonomic factors, physical agents and psychological barriers as well as two calculated variables of Activity-over-time and Duration of occupational exposure. There were two research questions: 1) is there an association between occupational exposures and risk of prostate cancer and 2) if so, is there a difference in risk between moderate grade tumours and high grade tumours? RESULTS The occupational exposure data were analysed as tertiles and/or quartiles using logistic regression. Analysis of differences between moderate grade and high grade tumours was done by polytomous logistic regression. Few significant associations were found; the exceptions were with physical workload, workload and duration. A weak relationship was found with ionizing radiation. Overall, the findings of this study indicate that few occupational exposures are related to prostate cancer.