The relative health risks and possible benefits of alcohol have been a source of much debate and dispute. The many adverse effects of drinking excessive alcohol are quite evident and require no further study or discussion. Despite a welter of prior studies, however, the effects of light-to-moderate alcohol intake remain less certain.

A study reported in the February 24 issue of the Journal of the National Cancer Institute deserves close attention. More than 1.2 million, middle-aged women in the United Kingdom, who were attending breast cancer screening clinics, completed questionnaires where they described their alcohol intake and provided information on other important health issues. The incidence of various types of cancers was determined during an average follow-up period of 7.2 years.

An increased risk of cancer

The most prominent finding was a greater risk of breast cancer among the women with regular light-to-moderate alcohol intake compared to those who drank little or no alcohol. The increased risk of breast cancer was the same in women whether they did or did not use hormone replacement therapy.

This finding is consistent with a recent pooled analysis of 53 epidemiological studies.

Light-to-moderate drinking was also associated -- weakly, but still with statistical significance -- with increased risks of cancer of the liver and rectum, but not with colon cancer. Also found was a greater incidence of cancers of the oral cavity, pharynx, larynx, and esophagus, but only among current smokers. No higher risk was found for cancers at other sites.

The cancer risks were the same for those who drank wine, beer, or spirits.

Most current guidelines recommend no more than one drink a day for women. This study did reveal a small increase in the incidence of cancer among women who were already limiting their alcohol intake to a daily drink; however, the risk was considerably greater in those who drank more.

Should you be concerned?

For several reasons, I believe the findings of this study cannot be ignored:

• The enormous number of women in the study
• The length of the follow-up period
• The adjustments made by the researchers to account for multiple possible     confounding factors such as age, body weight, and physical activity
• The ability to capture nearly all cases of cancer from a national registry

Moderate alcohol intake has been frequently cited as being beneficial to most adults in several ways: studies have shown, for example, that it reduces overall mortality and lowers the incidence of cardiovascular events. Unfortunately, the present publication mentioned neither overall mortality nor the frequency of cardiovascular events.

The study did find a lower incidence of several other cancers in women who drank alcohol - -thyroid cancer, non-Hodgkin lymphoma, and renal cell carcinoma -- but it is not clear whether alcohol was the reason for this protective effect.

The bottom line

Despite a small increased risk of certain cancers, a daily alcoholic drink in middle-aged women seems acceptable for the pleasures given and a possible reduced risk of cardiovascular events. Remember that one drink is generally defined as a 12-ounce can/bottle of beer or wine cooler, 4 or 5 ounces of wine, and a standard shot (1 and ½ ounces) of 80-proof liquor.

BUT... the results of this study do offer women further support not only for limiting their alcohol intake to no more than one drink a day, but also for not smoking. And women with major risk factors for breast cancer, such as a strong family history, should probably drink alcohol only on ceremonial occasions.