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Does alcohol increase breast cancer risk?

Bupa investigative news - 22 November 2002
written by Rachel Newcombe, Bupa health news reporter

Breast cancer is the most common form of female cancer and more than 38,000 women in the UK are diagnosed with it each year. According to the latest research into the effects of alcohol and smoking, it appears that drinking alcohol may raise the risk of breast cancer, but smoking does not. So how large a risk is drinking alcohol and should women be worried?

What were the headlines?

Because breast cancer is such a major issue, the news that alcohol, but not cigarettes, could increase a woman's risk quickly swept through the media. Newspapers and websites featured reports on the findings and carried headlines such as "Glass of wine a day breast cancer alert" and "Alcohol increases breast cancer risk".

While the majority of reports gave detailed information about the study, a few merely touched on the details, leaving the exact risks open to individual interpretation - something that may have caused unnecessary concern.

What is the bigger picture?

The study in question, dubbed as being the "world's largest", was carried out by researchers from Cancer Research UK and published in the British Journal of Cancer.

The team looked at drinking and smoking habits by combining the results of more than 50 studies and included data from nearly 150,000 women around the world.

Researchers were able to establish that smoking does not contribute to risk of breast cancer because the 23,000 women who did not drink had the same chance of developing breast cancer regardless of whether they smoked or not.

Although smoking doesn't contribute to the risk of breast cancer, alcohol does. The exact reason why is unknown, but it may be because alcohol raises the levels of oestrogen in the body. According to the team, the risk increases by 6 per cent for "every extra alcoholic drink consumed on a daily basis".

Report co-author Professor Valerie Beral, from Cancer Research UK's Cancer Epidemiology Unit at the Radcliffe Infirmary in Oxford, said, "This research tells us there is a definite link between alcohol and breast cancer and the evidence suggests that the more a woman drinks, the greater her risk."

On the surface it seems quite worrying, but put into perspective alcohol is only likely to account for about 2,000 cases of breast cancer per year, or 4 per cent of the total. Another factor worth considering is that alcohol can have beneficial effects on the cardiovascular system and has been shown to reduce the risks of heart disease.

Professor Beral admits, "the impact of drinking on breast cancer is small," but says that because women are drinking more now than they used to, future rates of the disease are likely to be affected.

According to co-author, Dr Gillian Reeves, "The balance between the harmful effects of alcohol on breast cancer and its beneficial effects on heart disease depend on a woman's age. Before about 60, breast cancer is a more important cause of death than heart disease. After the age of 65, when the risk of heart disease becomes much greater than the risk of breast cancer, the benefits of moderate drinking are more apparent."

What does this mean?

Although it's one of the largest studies to date, this isn't the first time alcohol has been associated with breast cancer; american researchers found similar results in 1998. Professor Peter Boyle, director of the European Institute of Oncology in Milan, has been aware of the issue for a while. He says the "evidence has been building up for the past decade" and that there's potentially a "much increased risk to come through in the next two or three decades" due to women tending to drink more.

While it's true that women are drinking more - figures from the Office of National Statistics (ONS) show that 86 per cent of women aged more than 16 years drank regularly in 1998 - most experts believe moderate drinking is unlikely to have a dramatic effect.

Breast cancer is uncommon in women aged less than 35 and is unlikely to be increased dramatically by drinking alcohol. "If you're young, then your absolute risk of breast cancer is very low anyway, so it's really not increasing it very much overall," explained Dr Bentley.

Binge drinking, however, could be more harmful. "Eighteen year olds who make a habit of binge drinking are building up a significant breast cancer risk in 20 to 30 years," says Professor Boyle.

The cancer risk rises after the menopause and, according to the Department of Health, over 60-year-olds have a one in 15 risk. However, heart disease is also a greater risk at that stage and because alcohol is beneficial for the cardiovascular system, "the benefits of drinking will [still] outweigh the risk of breast cancer," says Dr Bentley.

What does this mean to me?

"Women shouldn't panic," says Dr Bentley. "They should consider individually what it means to them, but they don't necessarily need to give up moderate drinking. The benefits and risks probably balance each other out."

"A practical measure women can take is to be breast aware - to be aware of what's normal for their breasts throughout the monthly cycle, and to see a doctor or nurse if they do notice any changes," she added. "If they do have a breast lump it's more likely not to be cancer than cancer - nine out of 10 lumps aren't cancer. Being vigilant about breast awareness is probably more important than worrying about drinking one glass of wine per day."

Delyth Morgan, chief executive of the charity Breakthrough Breast Cancer, agrees. "It's important to remember that early detection greatly increases the chances of surviving breast cancer," she says.

Jackie English, from Breast Cancer Care, stressed the importance of a healthy lifestyle: "We would advise women to try to maintain a healthy lifestyle to decrease their cancer risks. By limiting the amount of alcohol they consume, women can take positive action that may reduce their breast cancer risk as well as contribute to a healthier lifestyle."

Even though smoking wasn't found to contribute to breast cancer, it plays a huge part in other types of the disease, such as lung cancer. Because of this Cancer Research UK insists that "not smoking should still be a priority."

Summary

It's not surprising that the threat of breast cancer worries many women. Although alcohol has been linked to an increased risk, like other activities, there are benefits and risks involved and the current evidence suggests that it's safe to drink moderately.

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Links for more information

• British Journal of Cancer
• How to check your breasts article
• Breast awareness factsheet
• Breast lumps factsheet
• Breakthrough Breast Cancer
• Breast Cancer Care
• Cancer Research UK