Inflammation
The body's response to injury or infection: immune cells and fluid rush in, causing redness, heat and swelling. Short bursts heal; long-term smouldering inflammation promotes cancer.
Chronic inflammation from infection (hepatitis B and C, H. pylori, HPV), irritation (tobacco, asbestos, acid reflux) or disease (ulcerative colitis) supplies growth factors, free radicals that mutate DNA, and blood-vessel growth, and it is estimated to underlie around a fifth of cancers; 'tumour-promoting inflammation' is a recognised enabling characteristic in the hallmarks of cancer. Yet inflammation is also how the immune system attacks tumours, and an 'inflamed' or 'hot' tumour is one full of T cells that responds well to checkpoint inhibitors. Aspirin and other anti-inflammatory drugs reduce colorectal cancer risk, and the inflammatory markers CRP and IL-6 track cachexia and prognosis.