Cancer causes six million deaths worldwide each year, and is the second leading cause of death in developed countries. Of 227,000 new cases diagnosed in Canada this year, about 80 per cent will be some type of carcinoma, a malignant tumor that begins in the epithelial cells lining the inner and outer surfaces of our organs. Carcinomas comprise a vast array of cancers, including lung, breast, prostate, colorectal, oral, esophageal and cervical. Although current treatments can be effective, survival rates vary for these different types of cancer. Mutations in genes are responsible for the development of all cancers. But the nature of epithelial cancer cells makes it difficult to distinguish which mutations initiate the process. William Lockwood is using new technology to define patterns of DNA change in people with early stage epithelial cancer and to identify the genes responsible for the progression of the disease. Ultimately, these genes may be used to predict which pre-cancerous lesions are prone to develop into tumours to improve early detection and treatment.