Basal cell cancer is a malignant skin tumor involving cancerous changes of basal skin cells. Basal cell skin cancers usually occur on areas of skin that are regularly exposed to sunlight or other ultraviolet radiation. Once a suspicious lesion is found, a biopsy is needed to prove the diagnosis of basal cell carcinoma. Treatment varies depending on the size, depth, and location of the cancer. Early treatment by a dermatologist may result in a cure rate of more than 95%, but regular examination by a health care provider is required to watch for new sites of basal cell cancer.