Scientists have discovered that breast tumours in mice given the equivalent of two alcoholic drinks per day grow twice as fast as tumours in mice given no alcohol.
Commenting on the research, Ed Yong, Cancer Research UK's science information officer, said: "Thanks to studies involving large numbers of people, we have known for some time that alcohol increases the risk of breast cancer.
"This research suggests that it can also promote the growth of existing tumours. The results reinforce the message that women can reduce their risk of breast cancer by cutting down on how much they drink."
The study, conducted by scientists at the University of Mississippi Medical Centre and presented at the annual meeting of the American Physiological Society, used a new mouse breast cancer model which mimics human breast cancer.
Female mice were fed drinking water containing one per cent alcohol (the human equivalent of two alcoholic drinks per day) for a period of four weeks.
Moderate alcohol consumption nearly doubled the size of the tumours when compared to a group of mice who had not been given alcohol. This is the first animal model to confirm that alcohol consumption stimulates tumour growth and malignancy of breast cancer.
A 2002 study by Cancer Research UK-funded scientists estimated that alcohol causes about 2,000 breast cancer cases every year in the UK alone.
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