SEATTLE, March 14 /PRNewswire/ -- Obese men who are diagnosed with
prostate cancer have more than two-and-a-half times the risk of dying from
the disease as compared to men of normal weight at the time of diagnosis,
according to a study by researchers at Fred Hutchinson Cancer Research
Center. The findings by senior author Alan Kristal, Dr.P.H., and colleagues
appear online and will be published in the March 15 print edition of the
journal Cancer.
"I was very surprised by the findings," said Kristal, member and
associate head of the Cancer Prevention Program in the Hutchinson Center's
Public Health Sciences Division. "We found the prostate-cancer-specific
mortality risk associated with obesity was similar regardless of treatment,
disease grade or disease stage at the time of diagnosis," he said.
"If a man is obese at the time of diagnosis, he faces a 2.6-fold
greater risk of dying as compared to a normal-weight man with the same
diagnostic profile, regardless of whether he has a radical prostatectomy or
radiation therapy, whether or not he gets androgen-deprivation therapy,
whether he has low- or high-grade disease and whether he has localized,
regional or distant disease," Kristal said, referring to the degree of
cancer spread.
The researchers also found that obese men diagnosed with local or
regional disease -- that is, disease that is confined to the prostate or
has spread to into surrounding tissue -- face a 3.6-fold increased risk of
cancer spreading into distant organs, or metastasis, as compared to
prostate-cancer patients of normal weight. The association of obesity with
disease progression was strongest among men with regional stage at
diagnosis, whose cancer had already spread beyond the prostate, as compared
to men with early, localized disease.
The mechanisms behind the link between obesity and prostate cancer
metastasis and death are believed to involve both steroid hormones and
inflammation. "We are now beginning to appreciate that obesity is a massive
inflammatory condition," Kristal said, "and obesity also increases levels
of serum estrogens and growth factors that can promote cancer growth."
For the study, Kristal, first author Zhihong Gong, Ph.D., a
postdoctoral research fellow in the Hutchinson Center's Cancer Prevention
Program, and colleagues at the Hutchinson Center and the University of
Washington followed 752 recently diagnosed middle-aged, Seattle-area
prostate-cancer patients for about 10 years. Body-mass index, or BMI, in
the year before diagnosis was determined in an initial interview; 17
percent of the participants were classified as obese, with a BMI of 30 or
more. Of the men studied, 50 died of prostate cancer and 64 died of other
causes.
Only one other study has examined obesity and prostate-cancer outcome;
this study reported no association between the two, but the study was
limited to men at one hospital, all of whom received radical prostatectomy.
Kristal's study is the first long-term, population-based study of
prostate-cancer patients who have undergone a variety of treatments. A
strength of the study is that it used metastasis and mortality as an
endpoint versus biochemical recurrence (the presence of circulating
prostate-specific antigen, or PSA, in the blood after treatment, a
biomarker of limited value in predicting death from prostate cancer).
"I think this study represents the first good piece of evidence that
losing weight may in fact reduce the risk of dying of prostate cancer,"
Kristal said. "Although one would need a randomized clinical trial to
definitively determine whether weight loss could be an effective
complimentary treatment for obese men diagnosed with prostate cancer, these
results offer yet another good reason for men to achieve and maintain a
healthy weight," he said.
The National Institutes of Health, the National Cancer Institute and
Fred Hutchinson Cancer Research Center funded this study.
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 fhcrc.org.
MEDIA CONTACT
Kristen Woodward
(206) 667-5095
SOURCE Fred Hutchinson Cancer Research Center
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Related links:
http://www.fhcrc.org/
CONTACT:
Kristen Woodward of Fred Hutchinson Cancer
Research Center, +1-206-667-5095
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