Finding could spur research into other causes of the disease
TUESDAY, Jan. 29 (HealthDay News) -- A man's risk of prostate cancer is not related to the amount of sex hormones circulating in his bloodstream, a new British analysis suggests.
The conclusion was based on a review of 18 studies -- representing 95 percent of all available research -- that looked into potential links between the disease and blood hormone levels, the study authors said.
"There has been a long interest in whether or not natural variations in hormone levels in a man's blood are related to future disease risk," said study author Andrew Roddam, of the Cancer Research UK Epidemiology Unit at the University of Oxford. "What we have shown in this collaboration is that these natural fluctuations in levels of androgens [and estrogens] do not appear to be related to subsequent risk [for] the disease."
The findings were published online in the Jan. 29 issue of the Journal of the National Cancer Institute.
Prostate cancer is the most common type of cancer in American men, other than skin cancer. An estimated 220,000 new cases of prostate cancer were diagnosed in the United States in 2007, and about 27,000 men died from the disease, according to the American Cancer Society.
Although there's no single known cause of prostate cancer, risk is higher for those over the age of 50, black men, and those with a family history of the disease.
High levels of male sex hormones, known as androgens, have long been believed to be a risk factor for prostate cancer. To explore a possible hormone-cancer risk connection, Roddam and his colleagues analyzed data from studies that involved more than 10,000 men with and without prostate cancer. The research had been conducted between 1961 and 2001, and most study participants with prostate cancer had been diagnosed after the age of 60.
After compensating for other factors -- such as age, body-mass index, marital and educational status, smoking history and alcohol consumption -- the study authors found no statistical correlation between pre-diagnosis sex hormone concentrations in the bloodstream and the risk for developing prostate cancer.
Similarly, no hormone level combination -- such as a very high concentration of one sex hormone and a very low concentration of another -- was associated with prostate cancer risk.
In an accompanying editorial, co-author Dr. Paul A. Godley, an associate professor of medicine at the University of North Carolina School of Medicine, said the "impressive" findings could push prostate cancer research in a new direction.
"Researchers should redirect their attention toward investigations of potentially modifiable nutritional, lifestyle or environmental risk factors," he suggested, rather than target unchangeable factors -- such as blood hormone levels -- that do not appear to affect risk.
But, Dr. Peter T. Scardino, chairman of the department of surgery at Memorial Sloan-Kettering Cancer Center in New York City, cautioned that it would be wrong to conclude that male hormones have nothing to do with prostate cancer.
"This study asks if the amount of male or female hormones in your bloodstream can predict whether you will get prostate cancer, and the answer is no," he said. "But the prostate is like a sponge for hormones that sucks them out of circulation and converts them to even more powerful forms that can go to work in the prostate. So blood hormone levels may not have any connection with the amount of hormone in the prostate gland itself.
"The point is," he added, "I would not want people to think that altering the male hormone environment in the prostate has no effect. It certainly will. So if you take drugs like finestaride to shrink your prostate to urinate better, or Propecia to prevent balding, these drugs are working directly on hormone levels in the prostate, not the bloodstream. And these drugs work very well."
For additional information on prostate cancer risk, visit the American Cancer Society.
SOURCES: Andrew Roddam, Ph.D., Cancer Research UK Epidemiology Unit, University of Oxford, Great Britain; Paul A. Godley, M.D., Ph.D., departments of epidemiology and medicine, University of North Carolina School of Medicine, Chapel Hill; Peter T. Scardino, M.D., chairman, department of surgery, Memorial Sloan-Kettering Cancer Center, New York City; Jan. 29, 2008, Journal of the National Cancer Institute, online
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