Heavy Alcohol Use Increases Risk for Prostate Cancer, Negates Benefit of Finasteride

Roxanne Nelson

July 15, 2009

July 15, 2009 — Heavy consumption of alcohol appears to increase the risk for prostate cancer. In addition, heavy drinking negates the efficacy of finasteride (Proscar, Propecia) in reducing prostate cancer risk.

"If you are prescribing finasteride, counsel on heavy drinking, and if you are counseling on prostate cancer prevention, counsel on heavy drinking as well," said study author Alan Kristal, DrPH, associate head of the Cancer Prevention Program, Fred Hutchinson Cancer Research Center in Seattle, Washington.

The new study found that men who consumed at least 50 g of alcohol on a daily basis greatly increased their risk for high-grade prostate cancer. This effect was observed for patients receiving finasteride as a chemopreventive agent and for those receiving placebo. The study was published online July 13 in Cancer.

However, the investigators also found that the association between drinking and low-grade cancer differed by treatment group. For men receiving placebo, there was no relationship between alcohol use and low-grade prostate cancer. But for those receiving finasteride, drinking 50 g or more of alcohol daily almost doubled the risk for low-grade disease (relative risk [RR], 1.89; 95% confidence interval [CI], 1.39 - 2.56).

This finding, say the authors, was "because of a 43% reduction in the risk of low-grade cancer attributable to finasteride treatment in men who drank less than 50 grams of alcohol daily, and the lack of an effect of finasteride in men who drank more than 50 grams on a daily basis."

The reference group for this risk is the men receiving placebo who drank less than 50 g of alcohol per day, explained Dr. Kristal. "In the finasteride arm, men drinking less than 50 g of alcohol were at lower risk of low-grade cancer," he told Medscape Oncology. "But if men in the finasteride arm were heavy drinkers, their risk of low-grade prostate cancer was the same as the men not on finasteride. This is called a joint-effects analysis, because you can see the effects of the drug and the effects of alcohol independently."

"Within the finasteride arm, it looks like an increased risk," Dr. Kristal added, "but in the population overall, you can see that it was a reduced risk in the group drinking less than 50 g daily, and no effect in the heavy drinkers."

Current research is inconclusive regarding the relationship between alcohol consumption and prostate cancer risk. Although 2 meta-analyses have reported an increase in risk of approximately 20% among heavy drinkers (Prostate. 2000;42:55-56 and Br J Cancer. 2001;85:1700-1705), most studies have not found a significant association, the authors note. In this study, Dr. Kristal and colleagues evaluated the associations of total alcohol, type of alcoholic beverage, and drinking pattern with the risk for total, low-grade, and high-grade prostate cancer.

All of the data in this study were collected as part of the Prostate Cancer Prevention Trial (PCPT), which randomized 18,880 men aged 55 years and older to receive finasteride as a chemopreventive or placebo. Results of this study, which have been previously reported by Medscape Oncology, found that there was a 25% reduction in prostate cancer incidence among men in the finasteride group.

Risk Differs by Treatment Group

The current study evaluated 2129 participants who were diagnosed with prostate cancer during the 7-year trial and 8791 men who were determined by biopsy to be free of cancer at the end of the study period.

Their results showed that only heavy drinking, defined as 50 g or more of alcohol intake per day, was associated with an increased cancer risk. In the placebo group, heavy alcohol consumption was not associated with a risk for total or low-grade cancer, but was associated with a nonsignificant 67% increase in the risk for high-grade disease. Conversely, in the finasteride group, heavy drinking was associated with an 89% increased risk for total cancer, a 101% increased risk for low-grade cancer, and a 115% increased risk for high-grade cancer (P < .01 for all).

A post hoc analysis showed that the relative risk for high-grade cancer associated with heavy drinking in the combined study groups was 2.01 (95% CI, 1.33 - 3.05).

Type of Alcohol Affects Risk

They also looked at the effect of specific types of alcoholic beverages on the risk for prostate cancer risk. In both study groups, heavy consumption of beer was associated with a significant and large increased risk for high-grade cancer (RR, 2.89; 95% CI, 1.76 - 4.76; P < .0001). Among men in the placebo group, heavy wine consumption was associated with a 79% increased risk for low-grade cancer and, in the finasteride group, heavy beer drinking was associated with a 103% increased risk for low-grade disease (P < .0001).

When looking at the relation between alcohol consumption and finasteride treatment, the researchers observed that finasteride lowered cancer risk by 29% among men who drank less than 50 g per day, but increased risk by 17% among heavy alcohol drinkers. Finasteride reduced the risk for low-grade cancer by 43% among men who drank less than 50 g of alcohol per day, and increased the risk by 12% among heavy drinkers.

For high-grade cancer, use of finasteride increased the risk by 19% among men drinking less than 50 g of alcoholic beverages per day, but increased it by 78% among heavy drinkers.

I think this is yet 1 more outcome of heavy drinking.

These results suggest that finasteride will not lower prostate cancer risk among men who are heavy drinkers, they write, and the finding is not due to poor adherence. Although several underlying mechanisms are plausible, "future studies in the PCPT will examine whether heavy drinking affects finasteride metabolism or finasteride induces changes in steroid hormone metabolism."

"I think this is yet 1 more outcome of heavy drinking," said Dr. Kristal, but it should be noted that there was no risk identified with moderate or light drinking, or even with occasional binge drinking.

The study was supported by grants from the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Cancer. Published online before print July 13, 2009. Abstract

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