Can long-term inflammation in your body cause cancer?
Prolonged low-grade inflammation is a recognised risk factor for several types of cancer. The evidence is strongest for bowel cancer in inflammatory diseases and for multiple cancer types in obesity.
Yes, prolonged low-grade inflammation in your body is proven to increase your risk of cancer. This is not the short-lived inflammation you get from a cut, but a smouldering state in which your immune system stays active for years. That creates an environment in which cancer cells can arise and grow1.
This has been studied most concretely in obesity. In people who are overweight, fatty tissue behaves like continuously damaged tissue, packed with immune cells that produce inflammatory substances. Those substances drive insulin resistance and cell damage. Strong associations have been found with breast, bowel, liver and pancreatic cancer2,3. Notably, that fatty-tissue inflammation also occurs in people of normal weight, so the number on the scale is not the whole story.
The link is also well documented in chronic bowel diseases such as ulcerative colitis and Crohn's disease. The persistent inflammation in the intestinal wall alters the cellular environment so profoundly that it promotes tumour formation, increasing your risk of bowel cancer4. People with these conditions are therefore monitored especially closely.
There is also an epidemiological association between chronic gum inflammation and cancer, but convincing evidence in humans is still lacking5. Caution in interpreting this is warranted.
The good news: fatty-tissue inflammation is reversible. Weight loss through healthier eating and more physical activity demonstrably lowers cancer risk, presumably because chronic inflammation decreases2,3. Improving your lifestyle therefore tackles a proven risk factor.
Based on multiple review articles (PMID 31806905, 27903155, 40714142, 39465427, 26976915, 33510490). The strength of evidence differs by cancer type: strong for the general inflammation-cancer link and for IBD-related bowel cancer, moderate for obesity-related cancers, limited for gum inflammation. Exact risk figures are not provided in the sources. Large randomised studies on long-term cancer outcomes are not available in this source selection.