Reduce your risk of breast cancer this Dry July

Dry July

Dry July has become a fixture on the Australian charity calendar. It’s a great way to raise money for charity and an opportunity to re-examine our relationship with alcohol. You’ve likely heard that going dry can help your waistline, your bank balance and sleep. But what you may not know is that staying dry can help reduce your risk of breast cancer.

When people think of alcohol and cancer, they typically think of liver cancer or stomach cancer.  Few people, particularly young women, think of alcohol as a breast cancer risk factor. However, by going dry, Australian women can reduce their risk of breast cancer. As a breast cancer surgeon, this is a message I am passionate about getting out there.

Breast cancer risk  

Breast cancer is the most common (non-skin) cancer affecting Australian women today. And the numbers have skyrocketed in the last 30 years.  Back in 1982, it was 81 per 100,000 Australian females. Now, it’s 133 per 100,000, which is a 60% increase in under 40 years. Some of this can be explained by greater screening, with Breast Screens coming into existence in 1991; however, the increase since then is real and multifactorial.

We know there are many risk factors for breast cancer. Some we can change, and some are harder, but it’s worth brushing up on all of them.

Risk factors

Number one is being a woman.  For every 1 male who develops breast cancer, 133 women will.

The next most significant risk factor is age because with increasing age, so does our risk of developing cancer. This is common for all cancer types because every time our cells divide, there’s a risk of something going haywire and the older we get, the more cell divisions we live through.  So, at age 74 when breast screen invitations stop, please keep going if you are still well enough.

The next group of risk factors have to do with our oestrogen exposure – this includes the age we get our first period (menarche), age at first pregnancy, number of pregnancies, and breastfeeding. These may be harder to control than other risk factors like stopping alcohol consumption. However, cultural and societal factors can play a role in when and how many children we have so this is an important conversation for another day.

And then we come to the risks we have control over as individuals in our day-to-day life.  They are obesity, physical exercise and alcohol consumption. Being Dry July, it’s the perfect time to consider how alcohol affects our risk of breast cancer.

The link between alcohol and breast cancer

In 2012, the International Agency for Research on Cancer (IARC) declared that alcohol is a Group 1 carcinogen, in the same category as tobacco smoke, UV radiation and formaldehyde. But alcohol consumption is an enshrined part of life in Australia, with more than 75% of Australians drinking regularly.. Cigarette companies could only dream of reaching those dizzying heights.  Plus the Australian Bureau of Statistics (ABS) reports that the number of people drinking is going up, as more women and people from different backgrounds adopt Australia’s drinking culture (1).

So how does alcohol actually cause breast cancer?

The best theory is that alcohol consumption leads to higher levels of circulating oestrogen(2, 3), which has been shown to stimulate the growth of hormone responsive cells; and this includes oestrogen stimulated tumours(4). Additionally, the break-down products of alcohol cause cancer, particularly acetaldehyde, of which 97% is processed in the liver with the remainder in body fat and breast tissue. Acetaldehyde binds to both proteins and DNA and can interfere with our DNA repair and reproduction(2), as in how our cells replicate and keep themselves in order. Thankfully it’s not all doom and gloom, as the consumption of recommended amounts of fruit and fibre has been shown to decrease risk by almost 10% (5).

Excessive and binge drinking

As with so many other health and safety issues, those who drink in excess or binge drink are at greatest risk. In fact, we now have evidence that binge drinking increases your risk of breast cancer by 76%!  A study of university graduates out of Spain revealed an increase for all types of breast cancer and notably doubling the risk of early-onset breast cancer (known as pre-menopausal) (6).

Small amounts of alcohol consumption

Perhaps what’s more troubling, and what I want more women to know, is that even small amounts of alcohol consumption can increase your risk, particularly when women start drinking in their teens. It’s been challenging to tease out this data. Despite all the thousands of trials that have happened in the world over the years, very few have focused on women. One of the main reasons for this is the potential for pregnancy in women aged 15-50 – which of course translates to huge gaps in data and research! Thankfully, a study of women has occurred – the landmark Nurse’s Health Study (NHS). Established in 1976 at Harvard University, the NHS followed female nurses, who completed questionnaires on their health and behaviour every two years. After many years of rigorous data collection, they eventually published their findings in 2011, with alarming results that found for each additional drink a woman consumes on a daily basis, their risk goes up 10%(7).

Alcohol is the leading cause of breast cancer for pre-menopausal women and the second behind obesity for older woman. Every extra drink increases that risk. Let’s start talking about drinking and why we do it. And let’s do more than cancer fundraising. I challenge you, this Dry July and after, to take an active role in preventing cancer in your own life.

Sponsored by Dr Heidi Peverill

About the author

Dr Heidi Peverill is a Specialist Breast and Melanoma surgeon, with an interest in breast preservation and reconstruction. She takes time to listen and understand what is important for each patient, so together you can decide on the best treatment plan for you.

Outside of work, Dr Peverill enjoys spending time with her husband Michael, their young daughter, and their two dogs.

Read more from Dr Heidi Peverill

Offline sources

1. Yusuf F, Leeder SR. Making sense of alcohol consumption data in Australia. Med J Aust. 2015;203(3):128-30, 30e 1.
2. McDonald JA, Goyal A, Terry MB. Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence. Curr Breast Cancer Rep. 2013;5(3).
3. Liu Y, Nguyen N, Colditz GA. Links between alcohol consumption and breast cancer: a look at the evidence.(Report). 2015;11(1):65.
4. Jung S, Wang M, Anderson K, Baglietto L, Bergkvist L, Bernstein L, et al. Alcohol consumption and breast cancer risk by estrogen receptor status: in a pooled analysis of 20 studies. Int J Epidemiol. 2016;45(3):916-28.
5. Key TJ, Balkwill A, Bradbury KE, Reeves GK, Kuan AS, Simpson RF, et al. Foods, macronutrients and breast cancer risk in postmenopausal women: a large UK cohort. Int J Epidemiol. 2019;48(2):489-500.
6. Sanchez-Bayona R, Gea A, Gardeazabal I, Romanos-Nanclares A, Martinez-Gonzalez MA, Bes-Rastrollo M, et al. Binge Drinking and Risk of Breast Cancer: Results from the SUN (‘Seguimiento Universidad de Navarra’) Project. Nutrients. 2020;12(3).
7. Chen WY, Rosner B, Hankinson SE, Colditz GA, Willett WC. Moderate alcohol consumption during adult life, drinking patterns, and breast cancer risk. JAMA. 2011;306(17):1884-90.