Women who drink a glass of wine a day during their teens could increase risk of developing breast cancer
Women who drink just one glass of wine a day in their teens and early twenties could be increasing their risk of breast cancer by a third.
Scientists have found that consuming fairly small amounts of alcohol early on in life has harmful effects on breast tissue.
Those who drank the equivalent of one glass of wine a day between the age of their first period and when they gave birth to their first child increased their risk by a third.
US researchers believe that the breast tissue of young women, which is still developing, is highly susceptible to the harmful effects of alcohol.
Although experts have known for some time that alcohol raises the risk of breast cancer, this is one of the first studies to show how it can have an effect so early in life.
Researchers from the Washington University School of Medicine in St Louis examined the drinking habits of 116,671 women aged 25 to 44.
They were asked to recall how much alcohol they drank a day from the ages of 15 to 17, 18 to 22, and 23 to 30.
They were also told to note down the age when they first started their periods and when or if they gave birth to their first child as pregnancy is known to protect against breast cancer. It was also recorded whether they had ever been diagnosed with the condition.
From their answers, the researchers were able to work out roughly how much alcohol the women had drunk per day over the various stages of their lives.
The results showed that women who drank a glass of wine a day between their first period and the age at which they had their first child increased their risk of breast cancer by 34 per cent.
When alcohol is broken down by the body it creates a substance called acetaldehyde, which can trigger genetic mutations in cells that lead to tumours.
It also increases production of oestrogen, the hormone linked to tumour growth.
The researchers, whose study is published in the Journal of the National Cancer Institute, said: ‘These findings add support to the importance of exposure [to alcohol] between menarche [the first period] and first pregnancy in breast cancer development.
‘Reducing alcohol consumption during this period may be an effective prevention strategy for breast cancer.’
Richard Francis, head of research at Breakthrough Breast Cancer, said the link was likely to be caused by breast tissue being particularly susceptible to developing cancer between these key ages.
‘We recommend that women of all ages reduce their alcohol intake in order to help prevent breast cancer,’ he said.
‘Regularly drinking is also associated with a range of other health problems, so we’d urge anyone wanting advice or support on cutting down on alcohol to speak with their doctor.’
Just under 50,000 British women are diagnosed with breast cancer every year and there are around 11,500 deaths annually.
But there is growing evidence that women can drastically lower their risk by adopting healthier lifestyles.
Smoking, obesity, a lack of exercise as well as alcohol are all thought to trigger the illness.
Earlier this year scientists warned that excess drinking was behind soaring rates of breast cancer in the under 50s.