Post-menopausal women who have three to four alcoholic beverages a week of any sort have a significantly higher risk that their breast cancer will come back, U.S. researchers said Thursday.

They said women who have been diagnosed with breast cancer should consider limiting alcohol consumption to less than three drinks a week, especially if they are overweight or obese.

We didn't find any increased risk in women who consumed less than half a drink per day. There was no association at all with breast cancer recurrence, said Marilyn Kwan, a research scientist at Kaiser Permanente in Oakland, California, who presented her findings at the American Association for Cancer Research San Antonio Breast Cancer Symposium.

Other studies have shown that alcohol use can increase the chances a woman will develop breast cancer in the first place, but few studies have looked at the role of alcohol consumption in women who already have had a breast cancer diagnosis.

Kwan and colleagues studied 1,900 women in the Kaiser Permanente Northern California Cancer Registry who survived early-stage invasive breast cancer between 1997 and 2000. The women reported their own level of alcohol consumption.

The women were followed for eight years. Women who drank three to four alcoholic beverages experienced a 30 percent increase in the risk that their breast cancer would come back.

Half of these women drank alcohol -- wine, beer and liquor -- to some degree. The study compared these with breast cancer survivors who did not drink.

The more alcohol they drank, the higher their risk was for cancer recurrence, Kwan said.

She said other studies have shown alcohol can affect levels of estrogen circulating in the body and can increase the rate at which the body processes estrogen. Since many breast cancers are fed by estrogen, and she said she thinks moderate to heavy alcohol consumption may be fueling the cancers.

Kwan said for post-menopausal women who have had breast cancer, reducing alcohol consumption may be a smart move.

More than 400,000 women die from breast cancer worldwide each year.

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