||Mouth cancer is common worldwide and increasing in the UK. Some patients have abnormal white or red patches in the mouth which are at risk of becoming cancerous. We have already noticed that non-smokers with these patches are, surprisingly, at much higher risk than heavy smokers. In this project we aim to identify the clinical and molecular factors that might explain and predict cancerous changes. With this information we hope to design studies to help us choose between laser surgery, long-term review and discharge as the best & safest way to care for each patient.