Breast cancer awareness month: the evidence is clear that alcohol raises risk

04.10.2025 - As awareness activities roll out this October, which is internationally marked as breast cancer awareness month, experts across regions agree on a simple point. Drinking alcohol increases the risk of breast cancer, and risk rises with the amount consumed. While long established, the U.S. Surgeon General’s 2025 advisory brought renewed media attention and highlights alcohol as a cause of at least seven cancers, including female breast cancer, and calls for clearer public guidance and labelling. Global reviews from IARC and WCRF reach the same conclusion, noting there is no safe level for cancer prevention and that any type of alcoholic drink contributes to risk.

Large evidence syntheses quantify how risk increases. A 2025 analysis presented at the ESMO Breast Cancer Congress (European Society for Medical Oncology) reported a dose-response pattern: compared with non-drinkers, light drinkers had about a 6% higher risk of breast cancer, intermediate drinkers about 20%, and heavy drinkers about 47%. The National Cancer Institute’s fact sheet reports similar gradations, with relative risks of roughly 1.04 for light, 1.23 for moderate, and 1.6 for heavy intake. These figures sit within a broad international literature that has been consistent for years.

For the public, absolute risk helps make sense of the numbers. Using cohort data summarized in the Surgeon General’s advisory, NCI estimates that among 100 women who drink less than one drink per week, about 17 will develop an alcohol-related cancer during their lifetime. At one drink per day that rises to about 19 in 100, and at two drinks per day to about 22 in 100. Because breast cancer is common, even small relative increases translate into meaningful absolute increases.

Why alcohol matters for breast cancer is also well described. Ethanol is metabolized to acetaldehyde, which damages DNA. Alcohol can increase estrogen levels, which is relevant for hormone-receptor-positive breast cancers. Oxidative stress and impaired folate metabolism are additional pathways that reinforce the causal link evaluated by IARC.

Guidance is converging internationally. The European Code Against Cancer advises that if you drink, keep intake low, and that not drinking is better for cancer prevention. WCRF similarly states there is no safe level of drinking for cancer risk. In parallel, the Nordic Nutrition Recommendations 2023 advise avoiding alcohol when possible, or keeping intake very low, reflecting a shared prevention message that applies regardless of region.

The global burden is substantial. IARC estimates that alcohol caused about 741,300 new cancer cases worldwide in 2020, including approximately 98,000 female breast cancer cases. This is about 13% of all alcohol-attributable cancers and roughly 4% of all new breast cancer cases globally in 2020. underscoring why awareness efforts continue to highlight alcohol as a modifiable risk factor.

Bottom line If you do not drink, there is no cancer-prevention reason to start. If you drink, drinking less lowers risk, and there is no evidence of a risk-free threshold for breast cancer. This message is supported by recent advisories and long-standing evaluations from international cancer agencies.