What can I do myself to lower my risk of cancer?
By not smoking, limiting alcohol, maintaining a healthy weight and exercising enough, you can demonstrably lower your risk of several common cancers, even if cancer runs in your family.
A large cohort study of nearly 196,000 people shows that those who better follow the lifestyle recommendations of the World Cancer Research Fund have an 11% lower risk of cancer per step up in that score. This applied to 8 of the 13 cancer types studied1. Importantly, in people with a high hereditary predisposition, the absolute risk reduction was even greater than in people with a low genetic risk. Genetics is therefore no reason to do nothing.
The two most powerful steps are quitting smoking and sharply limiting or giving up alcohol entirely. Smoking increases the risk of several types of cancer. In women, it also makes an HPV infection more persistent, which raises the risk of cervical cancer. Alcohol consumption is consistently identified as a risk-increasing factor in multiple reviews2,3. Both factors appear at the top of every prevention list.
A healthy weight is the third major lever. Excess weight increases the risk of breast, colorectal and prostate cancer through hormonal disruptions and low-grade chronic inflammation. A diet rich in whole grains, vegetables, fruit and legumes, and low in red meat, processed products and sugary drinks, is associated with a lower risk4,5. The evidence for diet in isolation is associational, but fits consistently into the same picture.
Regular physical activity lowers the risk of cancer and can slow the progression of existing cancer, through improved metabolism and immune responses6. The precise magnitude of the effect varies across studies, but the direction is consistently positive.
Two measures deserve a caveat. The Mediterranean diet is cited as protective against ovarian cancer, but that evidence is limited and comes from a single review. Vitamin D supplementation has also been suggested, but specific dosages or guarantees are lacking7. For cervical cancer specifically, HPV vaccination and adequate antioxidants and folic acid can help reduce risk, in addition to not smoking. Finally, colorectal cancer in people under 50 has nearly doubled since the early 1990s, probably due to changes in diet and the living environment. Three in four young patients have no family history, which shows that lifestyle plays an independent role here.
The claims are based on multiple large cohort and review studies (PMID 36651198, 38542712, 40277318, 36040006, 29284222, 32738520, 31394082). The largest cohort included nearly 196,000 participants with an average follow-up of 10 years. For individual dietary factors and vitamin D, the evidence is moderate to limited and predominantly associational. There are no randomised trials for the complete lifestyle bundle.