What is the story?
Women who drink moderate amounts of alcohol are at a higher risk of developing breast cancer, according to media reports.
The findings come as a particular worry to women in the UK, where cases of binge drinking and alcohol-related deaths are increasing. A third of British women admit to drinking a moderate amount of alcohol or more each day. Breast cancer is estimated to kill more than 12,000 British women each year.
US researchers have found that giving the human equivalent of two alcoholic drinks a day to mice caused them to develop breast tumours twice the size of those in mice given no alcohol, said the papers.
Alcohol-fed mice had larger tumours due to an increased growth in blood vessels, the researchers argued.
Previous research had suggested that moderate drinking could be beneficial, helping to prevent heart disease.
What is the research?
The reports are based on US research presented at the American Physiological Society’s annual meeting in Washington.
Originally, the researchers were studying angiogenesis and noticed that alcohol they were using as a solvent was causing an increase in expression of a protein called vascular endothelial growth factor (VEGF).
These findings led to studies in mice that aimed to investigate the possible link between alcohol and cancer. The researchers proposed that alcohol could increase the levels of VEGF resulting in larger tumours.
For the latest study, mice were given drinking water that contained 1 per cent alcohol for 12 hours a day. This amount of alcohol is the equivalent of one or two alcoholic drinks a day in humans.
For the next 12 hours, the mice received water containing no alcohol. A separate control group of mice were given no alcohol at all.
After a week, all of the mice were injected with mouse melanoma cells into the mammary glands.
Three weeks later, the tumours were removed to be analysed. All of the mice were found to have tumours, but the mice that had been given the alcohol had tumours that had progressed more rapidly than the control mice.
The larger tumours were also found to have more blood vessel growth, indicating higher levels of VEGF in the alcohol-fed mice.
The tumours in the alcohol-fed mice weighed 1.4g on average, almost twice the size of the tumours in the control group.
What do researchers say?
Lead researcher Dr Jian-Wei Gu, assistant professor of physiology and biophysics at the University of Mississippi, said that scientists had known for hundreds of years that there was a strong association between alcohol consumption and several types of cancer.
‘This is the first study to use an animal model that accurately mimics human breast cancer.’
Alcohol consumption is the most important avoidable risk factor for women getting breast cancer, said Dr Gu.
Fellow researcher Thomas Adair, professor of physiology and biophysics at the University of Mississippi, said that the findings of the study had been confirmed by other scientists.
What other researchers say
Dr Sarah Cant, senior policy and information officer at the charity Breakthrough Breast Cancer, said: ‘We have known for some time that regularly drinking alcohol can slightly increase the risk of developing breast cancer and that this risk increases the more you drink.’
It is important to remember that this research is at an early stage and more studies are needed before we know whether its findings apply to women, said Dr Cant. But it is recommended that women only drink in moderation, she added.
‘It’s also important to remember that the biggest risk factor for most women is getting older. Most breast cancers occur in women over 50.’
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, he said.
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