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Obesity increases the risk of aggressive prostate cancer

'Apple-shaped' men with a family history of the disease at greatest risk

SEATTLE — Nov. 6, 2006 — Obesity is associated with an 80 percent increase in the risk of high-grade, aggressive prostate cancer, according to a recent analysis by researchers at Fred Hutchinson Cancer Research Center.

The findings, which were published in the October issue of Cancer Epidemiology, Biomarkers and Prevention, were based on data from the nationwide Prostate Cancer Prevention Trial, a randomized, controlled clinical trial designed to assess the ability of the baldness drug finasteride to prevent prostate cancer.

Senior author Alan Kristal, Dr.P.H., and colleagues in the Hutchinson Center's Public Health Sciences Division also found that among men who had a first-degree relative with prostate cancer, the distribution of body fat also contributed to increased prostate-cancer risk. Such "apple-shaped" men, who stored fat in the abdominal area, were found to have a nearly twofold increased risk of both low- and high-grade prostate cancer.

The study also found an increased risk of low-grade prostate cancer among the tallest men in the study — a finding that confirms previous research. "The correlation between height and prostate cancer probably has to do with the role of steroid hormones such as testosterone and estrogen that regulate both prostate development and height," Kristal said.

Interestingly, the study also found that obesity is linked to an 18 percent reduced risk of low-grade, nonaggressive prostate cancer, which accounts for about 80 percent of all cases. "This difference in the effect of obesity on low- and high-grade cancer answers a perplexing enigma about prostate cancer," Kristal said. "It helps explain why obese men are more likely to die of prostate cancer, as they are much more likely to get the form of prostate cancer that is difficult to treat and is often fatal."

The mechanisms behind the link between obesity and the most aggressive, fatal form of prostate cancer are believed to involve both steroid hormones and systemic inflammation. "Obesity is a massive inflammatory condition," Kristal said. "It also increases levels of circulating estrogens and growth factors that promote cell growth."

While previous studies have examined the link between obesity and prostate-cancer risk, the results have been inconsistent. This is the largest and most comprehensive analysis to date regarding the impact of obesity on prostate-cancer risk. The study involved more than 10,000 participants, approximately one-fifth of whom developed prostate cancer.

Strengths of the study include the fact that all of the men were screened for prostate cancer based on PSA level, digital-rectal exam and biopsy. In addition, all of the tissue analysis was done by a central pathology laboratory, ensuring consistent interpretation of cancer grade. Measurements such as height and weight also were collected by trained staff as opposed to relying on participants' self-report.

The National Cancer Institute funded the research.


Media Contact
Kristen Woodward
Fred Hutchinson Cancer Research Center
(206) 667-5095

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Fred Hutchinson Cancer Research Center
At Fred Hutchinson Cancer Research Center, our interdisciplinary teams of world-renowned scientists and humanitarians work together to prevent, diagnose and treat cancer, HIV/AIDS and other diseases. Our researchers, including three Nobel laureates, bring a relentless pursuit and passion for health, knowledge and hope to their work and to the world. For more information, please visit