Abstract B110: Dietary polyunsaturated fatty acids and risk of prostate cancer
Authors: Williams Christina D. , Whitley Brian , Hoyo Cathrine , Grant Delores , Iraggi Jared , Newman Kathryn , Gerber Leah , Taylor Loretta , Freedland Stephen 
Published: May 2012

Background: Prostate cancer is the most commonly diagnosed cancer among men in the United States, and disproportionately affects African-American men. It has been suggested that diet plays a role in prostate cancer development and progression. Evidence regarding the effect of polyunsaturated fatty acids (PUFA) indicate that n-3 PUFAs may suppress prostate cancer development while n-6 PUFAs may enhance prostate cancer carcinogenesis. Epidemiologic studies, however, have been inconsistent and the association between PUFAs and prostate cancer has not been adequately studied in racially diverse samples.

Objectives: The objectives of this work were to 1) examine the association between dietary intake of PUFAs [n-3 (ALA, EPA, DHA); n-6(AA, LA)] and risk of prostate cancer, and 2) determine if these associations differ between Whites and African-Americans.

Methods: Data are from an ongoing case-control study among veterans at the Durham VA Medical Center that includes biopsy-positive cases (N=66), biopsy-negative controls (N=91), and healthy controls (N=101). All men had a PSA test done in the year prior to study enrollment. Data were collected on various demographic, lifestyle, and other risk factors for prostate cancer using self-administered questionnaires. Diet was assessed using a food frequency questionnaire that asked participants to recall their diet in the past 12 months. Logistic regression analyses were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) among Whites (N=111) and African-Americans (N=146).

Results: The median percent of energy from total n-6 PUFAs was higher in cases compared to healthy controls (6.2% vs 5.7%, p=0.05). The ORs for cases relative to healthy controls were greater than one for high (i.e. ≥median) intakes of total n-6 PUFAs (OR: 1.79, 95% CI 0.92–3.48), yet close to null for total n-3 PUFAs (OR: 1.02, 95% CI 0.53–1.96). There were non-statistically significant inverse associations for specific PUFAs such as EPA, DHA, and LA (ORs 0.77, 0.68, and 0.62, respectively; all p-values &gt;0.05). A higher n-3:n-6 ratio was suggestive of lower prostate cancer risk (OR: 0.80, 95% CI 0.42–1.54). These findings were relatively unchanged in analyses comparing cases to biopsy-negative controls. In race-specific analyses comparing cases to biopsy-negative controls, there was evidence of effect modification by race for the relationship between LA intake and prostate cancer risk (OR: 0.78, 95% CI 0.30–2.04 in Whites; OR: 3.23, 95% CI 1.24–8.40 in African-Americans; Pinteraction=0.04). We did not observe any other statistically significant differences in prostate cancer risk between Whites and African-Americans.

Conclusion: Our overall findings do not suggest a strong role for n-3 or n-6 PUFAs in prostate cancer development, although racial differences in risk should be investigated in larger racially diverse samples.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B110.