HOUSTON - How heavy a man is at the time he is diagnosed with prostatecancer, as well as his history of weight gain, appear to playsignificant roles in how aggressive his cancer may become, sayresearchers at The University of Texas M. D. Anderson Cancer Center.
While a link between weight and initial development of prostate canceralready has been made, this report, published in the Oct. 1 issue ofClinical Cancer Research, is the first to associate a man's body massat different ages and adult weight gain with the risk of progressionafter his prostate cancer has been surgically treated.
"These findings support the view that the development of aggressiveforms of prostate cancer may be influenced by environmental effectsthat occur early in life," says the study's lead researcher Sara Strom,Ph.D., an associate professor in the Department of Epidemiology.
Given further validation of the results, Strom suggests a man'shistory of body weight should be a factor oncologists consider whendesigning a treatment plan for patients newly diagnosed with prostatecancer.
The data also suggest that interventions such as diet and exercisecould be a way to reduce the risk of prostate cancer progression, Stromsays.
Researchers based their findings on outcomes from 526 M. D. Andersonprostate cancer patients treated by surgery (prostatectomy). Theyfollowed the progress of the patients for an average of 4 1/2 years,checking whether the men entered "biochemical failure" or a risingprostate specific antigen (PSA) level, which can indicate the cancer isadvancing.
"After surgery, a patient's PSA should go back to being undetectable,but if it begins to rise, that is an indicator of progression," Stromsays. "Thirty percent of men who have biochemical failure will developa life-threatening cancer metastasis, and so PSA is the only marker wehave as yet to predict whose cancer will spread."
Within the group, 18 percent of the patients went into biochemicalfailure. Researchers then correlated an individual's risk ofexperiencing that failure with his weight history. They found that:
- Men who were obese (body mass index [BMI] of 30 or more) when they were diagnosed with prostate cancer were more likely to experience biochemical failure than those who were not obese;
- Patients who were obese at age 40 had an even greater rate of biochemical failure; and
- Men who gained weight at the greatest rate between age 25 and the time of their diagnosis experienced disease progression significantly sooner (an average of 17 months) than those men who gained weight more slowly (an average of 39 months).
Strom says that it is currently unclear how excessobesity contributes to prostate cancer progression, although leadingtheories suggest it could be linked to changes in a number of differenthormones (such as androgen and growth factors) and/or lifestylebehaviors (such as poor diet and inadequate physical activity). But sheadds that "understanding the mechanisms by which weight gaincontributes to prostate cancer progression will lead to rationallydesigned preventive strategies."
The study was funded by the National Cancer Institute. Co-authorsinclude principal investigator Patricia Troncoso, M.D., Xuemei Wang,Curtis Pettaway, M.D., Christopher Logothetis, M.D., Yuko Yamamura,Kim-Anh Do, Ph.D., and Richard Babaian, M.D.
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