Can long-term inflammation in your body cause cancer?
Prolonged inflammation is one of the most robustly supported risk factors for cancer. Well-known causes such as smoking, substantial obesity, and certain infections are modifiable, so addressing them concretely lowers your risk.
Prolonged, low-grade inflammation in your body substantially increases the risk of cancer, and plays a role at every stage: from the first malignant change in a cell to invasion of surrounding tissue and spread to other organs. This is supported by multiple large review studies and is considered one of the most clearly demonstrated links in cancer biology.
The inflammation can come from outside the body. Long-term infections (such as certain bacteria or viruses), smoking, obesity, excessive alcohol, and exposure to asbestos all cause a persistent inflammatory response that raises cancer risk. But it also works the other way around: a tumour that is already present can itself trigger inflammation, which further fuels tumour growth. Inflammation and cancer can thus trap each other in a self-reinforcing cycle.
Around a tumour, low-grade inflammation helps cancer cells survive more effectively. The tumour receives nutrients through new blood vessels, while the immune system that would normally clear the tumour is suppressed. Two molecular switches that are activated by inflammation help cancer cells resist the body's normal breakdown programmes and make the tumour more aggressive. Sustained damage from free radicals amplifies this effect.
Not every instance of inflammation is inherently harmful. A short-lived, acute inflammatory response can actually activate the immune system to attack cancer cells. This distinction between harmful chronic inflammation and potentially protective acute inflammation is, however, not yet fully understood. The practical implication is clearer on the prevention side: well-known sources of chronic inflammation such as smoking, severe obesity, and excessive alcohol increase cancer risk and are largely modifiable.
This answer is based on multiple broad review studies from research groups with no commercial interest. The link between prolonged inflammation and cancer is biologically well supported and consistent across multiple cancer types and mechanisms. The evidence for the precise molecular pathways (the switch proteins) comes from mechanistic research and is somewhat less direct than the epidemiological association. The researchers regard the relationship as probably causal, but in humans it is difficult to fully separate cause and effect, because inflammation and cancer also influence each other.
What is the role of chronic inflammation in the development of cancer?
Chronic inflammation is a proven driver of cancer: it promotes every step of tumour formation and makes tumours more resistant to treatment. Controlling persistent inflammation, for example through weight management or treatment of chronic infections, is therefore a relevant strategy for lowering your cancer risk.
Is it true that smoking causes cancers other than lung cancer?
Smoking is causally linked to at least fifteen cancers outside the lung; quitting smoking reduces that risk, and the sooner you quit, the greater the benefit.
Does eating heavily heated or charred food increase your risk of cancer?
Heavily heated or charred meat likely increases the risk of certain types of cancer, although the associations in humans are associative. By not charring meat and varying cooking methods, you can substantially reduce your exposure to these substances.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.
Does chronic inflammation accelerate the ageing of your cells?
Chronic inflammation demonstrably accelerates cellular ageing through a negative spiral that is difficult to break. The best evidence-based approach to tackling that spiral is through lifestyle factors that dampen low-grade inflammation, such as sufficient exercise and a diet low in ultra-processed products.
What does chronic sleep deprivation do to your inflammation in the long run?
Chronic sleep deprivation demonstrably raises inflammatory markers in your blood and is linked to diseases such as cardiovascular disease and dementia; getting enough sleep is therefore one of the most concrete things you can do yourself to limit chronic inflammation.