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Glycemic Index, Glycemic Load, Carbohydrate and Prostate Cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

Principal Investigator
Name
James Shikany
Institution
University of Alabama at Birmingham
Email
About this CDAS Project
Study
PLCO (Learn more about this study)
Project ID
2007-0048
Initial CDAS Request Approval
Dec 21, 2007
Title
Glycemic Index, Glycemic Load, Carbohydrate and Prostate Cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial
Summary
Prostate cancer remains a major public health problem in the US despite significant advances in treatment and decades of research into its etiology and prevention. Nearly 219,000 incident cases of prostate cancer and more than 27,000 prostate cancer deaths are projected for 2007, ranking prostate cancer as the leading incident cancer and second highest cause of cancer death in men (1). Many dietary factors have been speculated as influencing prostate cancer risk, including total and saturated/animal fat, meat, dairy products, and fruits and vegetables (2). Although most studies of diet and prostate cancer have focused on dietary fat, dietary carbohydrate may play a role in the etiology of this cancer. Carbohydrates elicit a wide spectrum of blood glucose and insulin responses, influenced by both their quality and quantity. Glycemic index (GI) is a ranking of carbohydrate-containing foods based on their postprandial blood glucose responses and is a measure of carbohydrate quality (3). Generally, the lower the GI, the lower the rate of absorption of the carbohydrate and the smaller the rise in postprandial glucose and insulin concentrations (4). Glycemic load (GL) is a measure that incorporates both the quality and quantity of dietary carbohydrates and is determined by multiplying the carbohydrate content of a serving of the food by the food's GI value. GL is probably the most relevant exposure as far as carbohydrate intake and disease risk is concerned (5). High dietary GI and GL have been associated with an increased risk of cancer at multiple sites, possibly by increasing insulin levels, which influence the insulin-like growth factor axis (6). We propose to study the association between dietary GI and GL (estimated from the PLCO DQx) and prostate cancer in PLCO subjects.
Aims

1. We will investigate the association of dietary GI (estimated from the DQx) with incident prostate cancer during follow-up in PLCO participants assigned to the screening arm. We hypothesize that dietary GI will be positively associated with prostate cancer risk. 2. We will investigate the association of dietary GL (estimated from the DQx) with incident prostate cancer during follow-up in PLCO participants assigned to the screening arm. We hypothesize that dietary GL will be positively associated with prostate cancer risk. 3. We will investigate the association of dietary carbohydrate (estimated from the DQx) with incident prostate cancer during follow-up in PLCO participants assigned to the screening arm. We hypothesize that dietary carbohydrate will be positively associated with prostate cancer risk.

Collaborators

Andrew Flood (Division of Epidemiology and Community Health; University of Minnesota)
Regina Ziegler (EBP/DCEG/NCI)

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