In addition, this research study is being done to determine if the expression of p53, a tumor suppressor gene (its activity stops the formation of tumors), is decreased following Efudex treatment. Mutations (abnormal changes) in the gene, called p53, are associated with a certain type of skin cancer. In addition, p53-mutated genes are known to exist in non-cancerous sun-damaged skin. Thus, the presence of p53 mutations may serve as a marker for both sun damage and an elevated risk of developing skin cancer.