Reduced Prostate Cancer Risk Is Linked To Weight Loss
Men's Health, Prostate Cancer and Weight Loss
A new American Cancer Society study of nearly 70,000 men finds men who lose weight may reduce their risk of prostate cancer.
The study, the first to examine the impact of adult weight change on prostate cancer risk, also finds obesity selectively increases the risk of more aggressive prostate cancer, while decreasing either the occurrence or the likelihood of diagnosis of less-aggressive tumors.
Prostate cancer is the most commonly diagnosed cancer other than skin cancer and the second leading cause of cancer death in U.S. men. About one out of six men will be diagnosed with prostate cancer during his lifetime, and one in 34 will die of the disease. While age, ethnicity/race, family history, and diet have all been identified with a higher risk of prostate cancer, studies on body mass index (BMI) have thus far been inconsistent in showing a link to increased risk.
In their new study, Carmen Rodriguez, MD, MPH, and colleagues from the American Cancer Society and the Duke Prostate Center used data from the Cancer Prevention Study II Nutrition Cohort to examine the association between adult BMI and prostate cancer incidence by stage and grade at diagnosis, as well as the association between weight change and prostate cancer incidence. The study is the first to use prospectively recorded weight change to assess the risk of prostate cancer. Men reported their weight in 1982 then again ten years later in 1992. They were followed for ten years, until June 2003, during which time more than 5,000 cases of prostate cancer occurred among the group.
After adjusting for variables such as age, ethnicity, smoking, diet, PSA screening, and other factors, researchers found BMI in 1992 was not associated with the overall risk of prostate cancer in the next ten years. But when they stratified the results by tumor grade, they found the risk of nonmetastatic low-grade prostate cancer (i.e. less aggressive cancer) decreased significantly with increasing BMI. In contrast, the risk of nonmetastatic high-grade prostate cancer (i.e. aggressive cancer) increased modestly with increasing BMI, and the risk of metastatic or fatal cancer increased steadily with increasing BMI.
They also found a link to weight change. Men who lost at least eleven pounds in the ten year period between 1982 and 1992 had just over half the risk of being diagnosed with nonmetastatic aggressive high-grade prostate cancer (RR, 0.58). Both weight gain and weight loss seemed to predict lower risk of nonmetastatic low-grade prostate cancer. No significant associations were seen between weight gain or weight loss and risk of metastatic or fatal prostate cancer.
"Obesity is one of the most prevalent modifiable cancer risk factors," said Dr. Rodriguez. "Previous studies have linked maintaining a healthy weight and weight loss to a decreasing risk of breast cancer. Our study linking obesity to aggressive prostate cancer adds to increasing evidence of the importance of maintaining a healthy weight through adult life. Although our study suggests that weight loss may lower the risk of aggressive prostate cancer, given the difficulty of losing weight, emphasis should be put on the importance of avoiding weight gain to reduce the risk of prostate cancer."
Article: Body Mass Index, Weight Change, and Risk of Prostate Cancer in the Cancer Prevention Study II Nutrition Cohort; Cancer Epidemiol Biomarkers Prev first published on December 19, 2006 as doi:1055-9965.EPI-06-0754.
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