Harmful alcohol consumption and breast cancer

Understand how harmful alcohol consumption can be related to the disease.

Cancer is one of the leading death causes worldwide, responsible for approximately 10 million deaths in 2020, or almost one in every six deaths. Breast cancer is currently the most prevalent tumor worldwide. Factors that increase the risk of breast cancer include old age, obesity, harmful alcohol consumption, family history of breast cancer, radiation exposure, gynecological history (age of menarche, first pregnancy, etc.), smoking, and postmenopausal hormone therapy (1).

Excess alcohol has carcinogenic potential, that is, it can cause various types of cancer. There is epidemiological evidence that alcohol consumption increases the risk of tumors in many organs, for example, in the oral cavity, larynx, esophagus, liver, pancreas and colorectum (2). According to the Global Cancer Observatory of the International Agency for Research on Cancer (IARC), an institution part of the WHO, 4.1% of new cases in 2020 were attributable to alcohol consumption.

Effects of alcohol on breast cancer (3)

Alcohol consumption is well established as a risk factor for breast cancer. The involvement of alcohol consumption in breast cancer is a complex process that acts through several mechanisms. And although alcoholic beverages contain a variety of compounds that contribute to carcinogenesis (the process of cancer formation), alcohol itself appears to be the most important component in this case.

However, the underlying mechanisms for alcohol to be carcinogenic still need to be clarified. Potential mechanisms include: oxidative stress, cell proliferation, effects on hormones (particularly steroid hormones), and effects on carbon metabolism.

When ingested, alcohol is metabolized into acetaldehyde, classified as carcinogenic by IARC. Although the production of acetaldehyde from alcohol occurs mainly in the liver, it also occurs in breast tissues and one of the adverse effects of acetaldehyde include modifications to DNA. Hormonal effects due to alcohol consumption may also contribute to breast cancer. Consumption of alcoholic beverages increases hormone levels. One study reported that consumption of 30g of ethanol (~2.5 drinks) per day for three menstrual cycles was associated with a 28% increase in plasma estradiol and a 21% increase in plasma estrone among women aged 21 to 40 years (4). Elevated intracellular estrogen levels resulting from alcohol intake may promote cancer-related cell proliferation in breast tissue.

Different patterns of alcohol consumption may have different effects on the development of breast cancer, even when the total amount of alcohol intake is constant (5). According to IARC, the risk of developing breast cancer increases by 7 to 10% for every 10g (∼1 drink) of alcohol consumed daily by adult women. This association is observed in both premenopausal and postmenopausal women. Compared to other organs, the breast appears to be more susceptible to the carcinogenic effects of alcohol. This raises a clinical and public health concern, because almost half of women of childbearing age drink alcohol and 15% of drinkers at this age drink four or more drinks at the same time (4).

In Brazil, for example, a study carried out by FIOCRUZ (6) with more than 1,500 women under 50 years of age showed that those who consumed alcohol regularly for 10 years or more had a three times greater risk of developing breast cancer compared to teetotalers or  occasional drinkers.

Healthy habits are essential for preventing breast cancer and other diseases, so try to practice physical activity, maintain adequate body weight, adopt a balanced diet and, if you decide to drink, consume in moderation.

References:

1. OMS (2023). Brest cancer. Disponível em: https://www.who.int/news-room/fact-sheets/detail/breast-cancer.
2. Connor, Jennie. "Alcohol consumption as a cause of cancer." Addiction 112.2 (2017): 222-228.
3. Freudenheim JL. Alcohol's Effects on Breast Cancer in Women. Alcohol Res. 2020 Jun 18;40(2):11.
4. Liu, Ying, Nhi Nguyen, and Graham A. Colditz. "Links between alcohol consumption and breast cancer: a look at the evidence." Women’s health 11.1 (2015): 65-77..
5. Starek-Świechowicz, B., Budziszewska, B., & Starek, A. (2023). Alcohol and breast cancer. Pharmacological reports : PR, 75(1), 69–84. https://doi.org/10.1007/s43440-022-00426-4
6. Vieira R, Tobar JSS, Dardes R, Claudio L, Thuler S. Alcohol Consumption as a Risk Factor for Breast Cancer Development: A Case-Control Study in Brazil. Asian Pac J Cancer Prev. 2018 Mar 27;19(3):703-707.