Author

Rachel Linz

Date

May 2009

Document Type

Thesis

Degree Name

M.P.H.

Department

Dept. of Public Health and Preventive Medicine

Institution

Oregon Health & Science University

Abstract

Background: Prostate cancer is the most prevalent cancer in men in the United States. It is estimated that in the US 186,000 men will be diagnosed with prostate cancer in 2008 and that the lifetime probability of being diagnosed with prostate cancer is 16.7%. Of the currently known risk factors for prostate cancer, such increasing age, race and family history, few are modifiable. Due to geographic variation in prostate cancer incidence, researchers have been investigating environmental factors, such as diet, that may play a role in prostate cancer risk. Folate is one such dietary factor that has been thoroughly investigated with regard to colorectal cancer due to its role in one carbon metabolic pathways. However, studies investigating the role of folate in prostate cancer risk have reported conflicting results. Methods: We conducted a case control study of men with biopsy confirmed prostate cancer, men with negative biopsies, and a third group of clinic controls with no history of prostate abnormalities. Study subjects completed an interviewer administered, validated, diet history questionnaire prior to biopsy (or primary care appointment), as well as providing demographic and risk factor information and a pre-biopsy blood specimen. Blood specimens were analyzed for folic acid content using an automated chemiluminescence assay, and the association between folic acid concentration and reported intake of dietary and synthetic folate and folic acid was examined. In addition, multiple logistic regression models were built to examine the significance of folic acid concentration on prostate cancer risk when combined with known risk factors. Results: Blood folic acid concentration was not significantly associated with prostate cancer. Correlations between blood folic acid concentration and reported dietary intake of folate or folic acid were low. Conclusion: Although others have reported a significant association between folate and prostate cancer, we did not observe such an association. The timing of exposure to folate may affect prostate cancer risk. Further longitudinal studies examining folate intake are recommended.

Identifier

doi:10.6083/M4J1014B

School

School of Medicine

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