HOUSTON, July 13 — Regular, heavy consumption of alcohol increased the risk of high-grade prostate cancer and blunted the chemopreventive effect of finasteride, data from the Prostate Cancer Prevention Trial (PCPT) showed.

• Explain to patients that heavy drinking may increase the risk of prostate cancer and interfere with finasteride’s ability to prevent prostate cancer.
• The findings came from a retrospective review of data, not a prospective clinical trial.

Men who consumed at least 50 grams of alcohol (at least four drinks) daily doubled their risk of high-grade prostate cancer, Zhihong Gong, PhD, of the University of California San Francisco, and colleagues reported online in Cancer.

The risk was similar in the placebo and finasteride arms of the trial.

Heavy drinking did not influence the risk of low-grade cancer in the placebo arm, but significantly increased the risk in men taking finasteride.

The overall risk increase in the finasteride group came about from a significant risk reduction in men who drank less than 50 grams of alcohol, combined with finasteride’s lack of effect among heavier drinkers.

The impact of heavy drinking on the risk of high-grade, screen-detected prostate cancer “is somewhat unique in the literature and requires replication,” the authors said.

“However, physicians may choose to consider this finding when counseling men on reducing their risk of prostate cancer.”

“It would be prudent for physicians who are recommending finasteride for prostate cancer prevention to assess their patients’ alcohol consumption and recommend drinking no more than two or three drinks per day,” they added.

Before this analysis, researchers were uncertain about alcohol’s effect on prostate cancer risk. Most individual studies showed no association, although at least two meta-analyses showed an increased risk of about 20% among heavy drinkers.

Dr. Gong and colleagues decided to clarify the association by analyzing the PCPT database. Additionally, they wanted to determine whether alcohol consumption affected finasteride’s ability to prevent prostate cancer.

The PCPT involved 19,000 healthy, middle-aged men who were randomized to finasteride or placebo for seven years. The trial ended prematurely when an interim analysis revealed a 25% reduction in prostate cancer incidence among men in the finasteride arm.

The authors’ analysis encompassed 10,920 participants in the PCPT. The study group consisted of 2,129 men who developed prostate cancer during the trial and 8,791 who had negative end-of-study biopsies.

Overall, heavy alcohol consumption and regular heavy drinking five or more days a week doubled the risk of high-grade prostate cancer (RR 2.01 and RR 2.05, respectively). The impact was similar in the placebo and finasteride arms. Lower levels of consumption did not influence the risk of high-grade prostate cancer.

The risk of low-grade cancer in the placebo group was unaffected by alcohol consumption. However, consumption of ?50 g of alcohol daily doubled the risk of low-grade prostate cancer in the finasteride group (RR 2.01, P=0.02 for trend).

“For low-grade cancer, finasteride decreased the risk by 43% among men who drank <50 g of alcohol per day and increased the risk by 12% among heavy drinkers,” the authors noted.

The authors acknowledged several limitations of the study. Heavy drinkers accounted for fewer than 3% of the study population, while data on alcohol consumption were limited to the year before enrollment in PCPT.

Because almost all of the cases of prostate cancer were screen detected, investigators could not examine associations between alcohol consumption and regional or distant disease.

The authors reported no financial disclosures.

Primary source: Cancer

Source reference:
Gong Z, et al “Alcohol consumption, finasteride, and prostate cancer risk” Cancer 2009; DOI: 10.1002/cncr.24423.