Abstract 2826: Carbohydrate intake, glycemic load, and glycemic index and prostate cancer risk

Abstract

Abstract Background: The typical U.S. diet is characterized by high carbohydrate intake, and dietary carbohydrates can modulate insulin sensitivity depending on their glycemic effect. Glycemic load and glycemic index, which represent the quality and quantity of carbohydrate foods, and prostate cancer risk are poorly characterized. Objective: To examine the association between dietary carbohydrate intake, glycemic load, and glycemic index and risk of prostate cancer, and determine if these associations differ between Whites and Blacks. Methods: We analyzed data from an ongoing case-control study of White (N=109) and Black (N=143) veterans at the Durham VA Medical Center. Cases were 65 men with biopsy-confirmed prostate cancer. There were two groups of controls: biopsy-negative controls (N=89) and healthy (i.e. no biopsy indication) controls (N=98). All men had a PSA test done in the year prior to enrolling in the study. Demographic and lifestyle risk factors were collected using self-administered questionnaires. Diet information was obtained using the Harvard food frequency questionnaire. Odds ratios (OR) and corresponding 95% confidence intervals (95% CI) for prostate cancer risk were obtained using logistic regression analyses adjusted for age, race, and total energy. Results: Mean carbohydrate intake, glycemic load, and glycemic index were similar among cases and both groups of controls (all p-values >0.05). We did not observe any statistically significant risk estimates for high (≥median) carbohydrate intake, glycemic load, or glycemic index. Compared to healthy controls, the ORs for prostate cancer risk associated with high carbohydrate intake, glycemic load, and glycemic index were 0.66 (95% CI 0.34-1.30), 0.57 (95% CI 0.22-1.49), and 1.18 (95% CI 0.61-2.02) respectively. Corresponding ORs when compared to biopsy-negative controls were 0.88 (95% CI 0.46-1.70), 0.69 (95% CI 0.29-1.64), and 0.83 (95% CI 0.43-1.59), respectively. The associations between carbohydrate intake, glycemic load, or glycemic index and risk of low-grade (gleason score <7) as well as high-grade (gleason score ≥7) prostate cancer relative to healthy controls were null for all analyses. There was no evidence of effect modification by race in our analyses. Additional adjustment for fiber intake did not appreciably alter any of the ORs. Conclusion: Our findings in a small case-control study do not suggest that a high carbohydrate intake and/or high glycemic load increase the risk of prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2826.