Uncorking the truth: US Surgeon General warns of alcohol’s hidden cancer risks

The link between alcohol consumption and cancer was first identified in the late 1980s, and the evidence supporting this connection has grown stronger over time.

Research now shows a clear causal relationship between alcohol use and an increased risk of at least seven different types of cancer, including breast cancer in women, colorectal, oesophagal, liver, oral cavity, throat, and voice box cancers.

The greater the alcohol consumption, the higher the cancer risk.

For certain cancers, like those of the breast, mouth, and throat, this risk can begin to rise with the consumption of as little as one drink per day.

This advisory aims to present the scientific evidence linking alcohol consumption to cancer risk and offer recommendations to help reduce alcohol-related cancer cases.

In the United States, the largest proportion of alcohol-related cancer cases is breast cancer in women, with an estimated 44,180 cases in 2019, accounting for 16.4 per cent of the approximately 270,000 total breast cancer cases.

Globally, alcohol consumption was linked to 741,300 cancer cases in 2020, with 185,100 of these cases resulting from the consumption of two or fewer drinks per day.

In women, breast cancer represents the majority (~60 per cent) of alcohol-related cancer deaths, while liver cancer (~33 per cent) and colorectal cancer (~21 per cent) make up most alcohol-related cancer deaths in men.

Approximately 83 per cent of the estimated 20,000 alcohol-related cancer deaths in the US each year occur in individuals who exceed the recommended daily alcohol limits (two drinks for men and one for women), with the remaining 17 per cent occurring within the current guidelines.

Moderate drinking and cancer

A report commissioned by the US Congress and conducted by the National Academies of Science, Engineering, and Medicine reviewed research dating back to 2010 on moderate drinking and its relationship to various outcomes, including heart disease, cancer, and Alzheimer's disease.

The new report might encourage those participating in Dry January or planning to reduce or quit drinking.

Experts say that while some of alcohol’s damaging effects may be permanent, others can be reversed.

Dr Wei Zheng from Vanderbilt University Medical Centre explained that cutting back on drinking can help reduce future risks.

Dr Vivek Hallegere Murthy, the US Surgeon General, emphasised that there is no "safe" level of alcohol consumption that guarantees no cancer risk.

Research shows that less alcohol consumption directly leads to lower cancer risk. Women are particularly vulnerable to alcohol's effects due to differences in how their bodies process alcohol compared to men, as noted by Dr Jamie Koprivnikar, an oncologist.

Studies have also revealed a rise in alcohol-related deaths among women in recent years.

Alcohol contributes to cancer in several ways, including DNA damage, hormone alterations, and the absorption of carcinogens from tobacco.

Warning labels

The US Surgeon General's report also recommends new alcohol warning labels and revising the current dietary guidelines to reflect the cancer risk associated with alcohol consumption.

Despite the existing recommendation of one drink per day for women and two for men, Murthy stated that consuming alcohol at these levels still increases cancer risk.

The call for updated warning labels on alcohol products was welcomed by experts such as Dr Bruce Scott, president of the American Medical Association, who argued that many people remain unaware of the cancer risks tied to alcohol consumption.

The proposed changes to the labelling, along with the Surgeon General’s report, could help raise awareness and improve public health.

Numerous high-quality studies over the past two decades have confirmed the link between alcohol consumption and an increased risk of cancer.

A global meta-analysis of 572 studies, covering data from over 486,000 cancer cases, consistently supports this conclusion.

Studies have found that daily alcohol consumption of about one drink increases the risk of mouth and breast cancer, while higher alcohol intake is associated with greater overall cancer risk.

Alcohol causes cancer through several biological mechanisms.

First, when alcohol breaks down into acetaldehyde, a metabolite, it binds to DNA and causes damage that can trigger cancerous cell growth.

Second, alcohol generates reactive oxygen species, which promote inflammation and cause further DNA, protein, and lipid damage.

Third, alcohol alters hormone levels, particularly oestrogen, which is a key factor in the development of breast cancer.

Lastly, alcohol can enhance the absorption of carcinogens from other substances, such as tobacco smoke, increasing the risk of cancers in the mouth and throat.

The World Health Organisation (WHO) published findings in The Lancet highlighting that no amount of alcohol consumption was safe for health.

Alcohol was identified as a toxic, psychoactive substance with addictive properties and had long been classified as a Group 1 carcinogen by the International Agency for Research on Cancer. This classification placed alcohol in the highest risk category, alongside asbestos, radiation, and tobacco.

Alcohol was found to be linked to at least seven types of cancer, including common forms such as bowel cancer and female breast cancer. Its cancer-causing effects stemmed from biological processes as ethanol broke down in the body, indicating that any alcohol-containing beverage, regardless of its cost or quality, posed a risk of cancer development.

Cancer ranks as the third leading cause of death in Kenya, representing a significant public health challenge that heavily impacts families, communities, and the healthcare system.

In 2020, the country recorded 42,000 new cancer cases and 27,000 deaths linked to the disease. Breast cancer remains the most prevalent type in Kenya, constituting 16 per cent of all new cancer cases and 11 per cent of cancer-related deaths annually.