Alcohol and breast cancer – how big is the risk?

‘Half a glass of wine a day increases breast cancer‘ was just one of the headlines this week, which discussed a report that reinforced the evidence that alcohol can increase a woman’s risk of developing breast cancer.

The report from the World Cancer Research Fund outlined the latest evidence on how we can reduce that risk – focusing on weight, physical activity and drinking.

The WCRF studies all the evidence on a potential risk and decides whether it’s strong enough to be a basis for making recommendations to the public.

Breast cancer is the most common cancer in the UK, and 1 in 8 women will be diagnosed with breast cancer at some point in their lives. And since we know that almost a third of breast cancer cases in the UK could be prevented, largely by changes to lifestyle, this is important stuff.

While the cause of an individual’s cancer can never be certain, there are still things you can do to reduce your risk. And evidence like this is the first step to helping women to do just that.

So what exactly does the report say?

Alcohol

The report backs up previous research showing that drinking alcohol can cause 7 types of cancer  including breast cancer. Even though it’s in the headlines, this is nothing new.

While the reports may sound alarming, we also know that the more you cut down, the more you’re reducing your risk.

Copy this link and share our graphic. Credit: Cancer Research UK

Although most women don’t regularly drink very large amounts of alcohol, thousands of cases of cancer – including breast – are linked to alcohol each year.

There are 3 good theories on the link between alcohol and cancer which we’ve written about before.

• When we drink alcohol, it’s broken down into a toxic chemical called acetaldehyde. Acetaldehyde can damage the DNA inside our cells, and then prevent damage from being repaired. This is important because it allows cancer to develop.
• Alcohol can increase the levels of certain hormones in the body, including oestrogen. We know that high levels of oestrogen can fuel the development of breast cancer, so this might be particularly important here.
• Alcohol also makes it easier for cells in the mouth and throat to absorb other cancer-causing chemicals. This is probably more important for other cancer types linked to alcohol rather than breast cancer.

Physical activity

The evidence on the link between breast cancer risk and both weight and physical activity is a bit more complicated. This is because there is evidence that the causes of breast cancer that occur in women before the menopause, compared to after the menopause, are different.

But overall there is strong evidence that keeping a healthy weight and being physically active, can help prevent breast cancer.

Unlike its previous report, this time WCRF says that some forms of physical activity probably reduce the risk for pre-menopausal breast cancer But the finding is only true for ‘vigorous’ activity – exercise which gets you breathing hard and your heart beating fast, so that you won’t be able to say more than a few words without pausing for breath.

The report also adds to the existing evidence that physical activity at any age is related to a lower risk of breast cancer in women after the menopause. This can be anything that gets you a bit hot and out of breath – from fast walking, to cycling, or even heavy housework. And the more you do the better.

Body weight

The evidence on weight and breast cancer is also complicated: as your risk changes depending on the ages at which you were overweight.

But overall the report agrees with previous work showing that being overweight or obese throughout adulthood causes postmenopausal breast cancer, something that is already well established.

Bringing it all together

Other things that affect a woman’s breast cancer risk are less easy to control. As with most cancers, the risk of developing the disease increases with age. Having a family history of the disease can increase a woman’s risk, and breastfeeding can reduce it.

All the different things that can increase the risk of breast cancer are held together by a common thread: they all affect the hormones circulating around in the body in some way.

Hormones help control what happens inside our bodies by sending messages from one place to another – including instructing cells when to stop and start multiplying.

If this system goes wrong, cells can get too many messages telling them to make more cells. And that can lead to cancer.

Overall the best advice is the same as at the start of the week: to keep active, keep a healthy weight throughout life, and limit alcohol.

Clare