A new Danish study suggests that the more alcohol a woman consumes per week, the higher her chances of developing breast cancer.
The study is published in the The European Journal of Public Health.
The researchers, led by Dr Lina Morch of the Centre for Alcohol Research in Denmark, followed a group of 17,647 female nurses from 1993 to 2001. They were aged 45 and over and completed questionnaires about their alcohol intake and pattern, and other lifestyle factors at the start of the study. During the follow-up period 457 women were diagnosed with breast cancer.
Using a statistical method known as Cox’s proportional hazard assessment, the researchers were able to assess the breast cancer risk of different levels and patterns of alcohol consumption.
The results showed that:
— Ten per cent of the women were binge drinkers. That is they drank more than 4 drinks a day.
— 13 per cent of them were weekend binge drinkers. That is they drank more than 10 drinks between Friday and Sunday.
— A woman who drank between 22 to 27 drinks a week was 2.3 times more likely to develop breast cancer than a woman who only had 1 to 3 drinks a week.
— For each extra drink of alcohol a week, the risk of breast cancer went up by 2 per cent.
— If this extra drink was at the weekend, the risk went up by 4 per cent.
— Drinking 4 to 5 drinks on the last day of the week (bingeing before the weekend) increased the risk by 55 per cent compared with having only one drink on this day.
A drink in Denmark is about 12g of alcohol, or 1.5 times the 8g unit used in the UK.
This is roughly equal to a bottle of beer or a glass of wine or spirits.
The researchers concluded that:
“For alcohol consumption above the intake most frequently reported, the risk of breast cancer is increased. The risk is minor for moderate levels but increases for each additional drink consumed during the week.”
“Weekend consumption and binge drinking imply an additional increase in breast cancer risk,” they added.
Speculating on the explanation for the link between alcohol and breast cancer, the researchers suggest that alcohol increases levels of estrogen, the hormone involved with the development of breast cancer.
The researchers pointed out that while their figures show a significant link between the total weekly alcohol consumption and breast cancer risk, there was also a pattern effect coming through, in that drinking a lot of alcohol in a short space of time is linked to the highest risks.
This ties in with their theory that the more alcohol there is in the bloodstream at any one time, the higher the estrogen levels.
How Much Alcohol is In a Drink?
In the UK, a unit of alcohol is 8g or 10 ml of pure alcohol. How much alcohol is in a drink depends on how big the drink is, and its alcohol concentration. Alcohol is measured in ABV, or alcohol by volume.
For example:
— Half a pint of normal beer or cider (3.5 per cent ABV) is 1 unit.
— A 400 ml bottle of alcopop (5 per cent ABV) is 2 units.
— A small 125 ml glass of wine (9 per cent ABV) is 1 unit.
— A 500 ml can of normal lager (4 per cent ABV) is 2 units.
— A 500 ml can of extra strong lager (8 per cent ABV) is 4 units.
— A 25ml pub measure of spirit (40 per cent ABV) is 1 unit.
However, many drinks come in different strengths. For instance beer and lager can range from 3.5 to 9 per cent, wine from 9 to 13 per cent.
So what might seem to be a small jump in glass size could end up being double the units. For instance, a more typical glass of wine consumed at home or in a restaurant or pub is nearer to 160 ml of 12 per cent ABV, which is nearly 2 unit.
The recommended weekly limit for men is 21 units and for women it is 14 units. It is also recommended that you have at least one clear alcohol free day a week.
“Alcohol drinking, consumption patterns and breast cancer among Danish nurses: a cohort study.”
Lina S. Mørch, Ditte Johansen, Lau C. Thygesen, Anne Tjønneland, Ellen Løkkegaard, Claudia Stahlberg, and Morten Grønbæk.
The European Journal of Public Health Advance Access published on April 18, 2007.
doi:10.1093/eurpub/ckm036.
Click here for Drugscope – Independent UK expert information site on alcohol and other drugs.
Written by: Catharine Paddock
Writer: Medical News Today