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Middle-Age Weight Gain May Increase Prostate Cancer
Risk
Reported September 04, 2009
(Ivanhoe Newswire) -- Body mass and weight gain in middle age may
influence a man's risk for prostate cancer, but this risk varies among
different ethnic populations, according to a new study.
"The relationship of certain characteristics, such as body size, with cancer
risk may vary across ethnic groups due to the combined influence of both
genes and lifestyle," lead researcher Brenda Y. Hernandez, Ph.D., M.P.H.,
assistant professor at the Cancer Research Center of Hawaii, University of
Hawaii was quoted as saying.
While obesity is a risk factor for common cancers like colorectal cancer and
breast cancer in post-menopausal women, the influence of body size on
prostate cancer risk is not entirely understood. Hernandez and colleagues
examined this relationship in a multiethnic population consisting of blacks,
Japanese, Hispanics, Native Hawaiians and whites, and compared differences
among age groups. They used the Multiethnic Cohort, a study of men, aged 45
to 75 years, in Hawaii and California from 1993 to 1996.
Results showed that of the 83,879 men who participated in this study, 5,554
developed prostate cancer. Overall, men who were overweight or obese by age
21 had a decreased risk of localized and low-grade prostate cancer,
according to Hernandez.
Excessive weight gain between younger and older adulthood increased the risk
of advanced and high-grade prostate cancers in white men and increased the
risk of localized and low-grade disease in black men, but decreased the risk
of localized prostate cancer in Japanese men.
"Readers of Cancer Epidemiology, Biomarkers & Prevention might initially
look at these results and discount them for being inconsistent across the
racial/ethnic groups, but they should not," Elizabeth A. Platz, Sc.D.,
M.P.H., associate professor of epidemiology at the Johns Hopkins Bloomberg
School of Public Health, Baltimore, was quoted as saying.
Platz stressed the strength of this study, including that it was conducted
prospectively and consisted of large numbers of men in most of the ethnic
groups studied. An estimated 30 percent of prostate cancer cases occurred
among Japanese men, 25 percent among white men, 27 percent among Hispanic
men, 13 percent among black men, and 7 percent among Native Hawaiian men.
This study underscores the importance of investigating cancer etiology in
diverse populations. "There is no reason to think that the differences in
results by ethnicity are explained by bias. Different racial and ethnic
populations tend to have differing proportions of fat relative to lean mass
and carry their fat mass differently. These differences may be used as a
launching point for the next line of research: The nature of the weight gain
— amount of fat gained and distribution of the fat gained in association
with prostate cancer risk overall, and by stage and grade," added Platz.
"These results do not warrant a change in the current public health messages
about obesity,” Platz continued. “Men of normal weight in all racial and
ethnic groups should be encouraged to avoid weight gain, and men who are
overweight and obese should be encouraged to lose weight for good health in
general."
SOURCE: Cancer Epidemiology, Biomarkers & Prevention, September 1, 2009 |
