MONDAY, July 13, 2009 (HealthDay News) -- Heavy drinking, especially when it's beer, increases the risk for highly aggressive prostate cancer, a new study finds.
The researchers did not set out to determine the effect of alcohol consumption on prostate cancer risk but rather to test the effectiveness of finasteride (Proscar, Propecia), a drug prescribed to prevent prostate cancer.
And they found that heavy drinking reduces the cancer-preventing effect of finasteride. But the researchers did not stop there.
"Within the data in that trial, we could address a large number of questions," said Alan R. Kristal, associate head of the cancer prevention program at the Fred Hutchinson Cancer Research Center and an author of a report on the study published online July 13 in Cancer.
One question was the possible relationship between alcohol consumption and prostate cancer risk. The study, which included more than 10,000 men, found that those who drank heavily -- 50 grams (1.7 ounces) of pure alcohol a day, the amount in four shots of hard liquor, five or more days a week -- were more than twice as likely as less heavy drinkers to develop what is called high-grade prostate cancer. There was no difference in prostate cancer risk between nondrinkers and those who drank moderately.
"The majority of [prostate] cancers are low-grade," explained Kristal, who is also a professor of epidemiology at the University of Washington. "They grow very slowly, and 100 percent of men with it live for 10 years. Most men die of something else. With high-grade prostate cancer, survival at 10 years is only 60 to 70 percent."
Most heavy drinkers in the study drank beer, Kristal said. "They are six-pack-a-day drinkers," he said. "But there is no logical reason to think there is anything special about beer that increases the risk that does not apply to other forms of alcohol."
True, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. The number of men in the study was too small to establish a relationship between prostate cancer and overall alcohol consumption, he said, but the finding might be enough to put prostate cancer on the list of malignancies that are affected by alcohol intake.
"Certain cancers are commonly associated with alcohol -- head and neck cancer, esophageal cancer, breast cancer," Lichtenfeld said. "Similar consistent information in regard to prostate cancer and alcohol really doesn't exist. But this was a well-defined and carefully developed study, an excellent opportunity to help answer that question."
The study provides "what is probably the best information we have on the possible relationship," Lichtenfeld said. "And one of the take-away messages we have is that drinking a lot of alcohol is a risk factor for developing aggressive prostate cancer."
It's not possible, Lichtenfeld said, to say anything about heavy drinking of wine and hard liquor because of the small number of such drinkers in the study. But people who drink equivalent amounts of alcohol in wine or hard liquor should not take comfort from that lack of statistical significance, he said.
"To reduce the risk of prostate cancer, it is best for you to reduce your intake of large amounts of alcohol," he said.
The American Cancer Society has more on the established risk factors for prostate cancer.