The obesity study examined the association between body mass index and prostate cancer in 787 men undergoing biopsy due to an elevated tumor marker in the blood or an abnormal physical exam at a Veterans Affairs hospital in California between 1998 and 2002.
It indicated that obesity increases the risk of prostate cancer, particularly in young men, as well as the risk of aggressive disease in all men.
“The exact relationship between obesity and prostate cancer is still very much a point of controversy and debate in urology,” said Dr Martha Terris, urologist at the Veterans Affairs Medical Center in Augusta and the Medical College of Georgia.
“One consensus that seems to be evolving is that obese men have an increased risk of more aggressive, and therefore potentially more deadly, disease,” Dr Terris said. “The take-home message for men and for all of us really is that we should try to maintain a healthy weight for a variety of health reasons.”
Obesity may literally be a deterrent to finding prostate cancer because it makes digital rectal exams, a major screening tool, more difficult, said Terris. In addition, in men and women alike, fat makes estrogen-like compounds, which lowers circulating levels of prostate specific antigen (PSA), a marker for prostate cancer. If PSA levels are lower due to hormone changes from obesity, the prostate cancer is less likely to be detected at an early stage.
Hormone changes observed with obesity also cause decreased levels of the male hormone testosterone. Since testosterone feeds prostate cancer, obesity could, in theory at least, reduce the risk of prostate cancer. This reasoning remains controversial, however, since the current study and others suggest that obese men actually may be at increased risk for prostate cancer. Researchers are more convinced of the link between obesity and aggressive prostate cancers that do not rely on testosterone to grow.