MedWire News: Women who drink alcohol have a greater risk of developing breast cancer than their teetotal counterparts, with the risk increasing with the amount of alcohol consumed, research suggests.

Previous studies have shown a relationship between breast cancer risk and alcohol consumption. But it is unclear whether the volume and type of alcohol consumed influences the risk.

To investigate, Dr Yan Li, from Kaiser Permanente Medical Center in Oakland, California, USA, and team studied data on more than 70,000 women, aged an average of 40 years, who underwent medical examinations and completed health questionnaires, including questions on alcohol intake, as part of a medical care programme.

Although none of the women had breast cancer initially, 2829 developed the disease over a follow-up period of 16 years.

Analysis revealed that, compared with women who never drank alcohol, those who drank less than 1 drink a day were 8% more likely to develop the disease, those who drank one to two drinks per day had a 21% increased risk of the disease and women who drank three or more drinks had a 38% increased risk.

The risk of breast cancer associated with alcohol intake appeared to be limited to tumours that require the hormone oestrogen to grow, called oestrogen-receptor-positive tumours.

The type of alcohol consumed, such as beer, wine or spirits, did not influence women’s risk of developing breast cancer.

The findings remained true after accounting for ethnicity, smoking and other factors, note the researchers.

Writing in the European Journal of Cancer, Dr Li and team conclude: “This study confirms an increased risk for breast cancer among women reporting daily drinking.”

They add: “The data suggest a risk threshold, with no increased breast cancer risk among women consuming less than one drink per day.”

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