The aim of this study is to identify predictive genes that will form the basis of a blood test to enable doctors to determine if oral cancer has spread beyond the mouth. Knowing about spread of cancer allows doctors to plan extra treatment such as radiotherapy beyond the surgery to remove the cancer. The principal investigator has now accumulated genetic data on over 900 patients with oral cancer. This data has been retrieved from several centres around the world and is a unique collection. Using advanced computing and bioinformatics techniques we will determine patterns of genetic changes that are most strongly predictive of spread of disease and could be used as biomarkers. Such biomarkers would indicate the likely risk of spread of disease and so determine whether further radiotherapy type treatment is needed.