The incidence of skin cancer has increased greatly. This is considered the primary cause of most skin cancers. Exposure to arsenic, which may be present in certain herbicides, is another risk factor for developing skin cancers. They may also occur on the scalp. The onset most commonly occurs after age 40.
Basal cells are normal skin cells.
They may develop cancerous changes, causing a patch or lump that is painless. The lump may grow slowly, ulcerate, and never heal completely. It usually remains local and almost never spreads to other parts of the body, but it may continue to grow and invade nearby tissues and structures, including the nerves, bones, and brain. The tumor may be very small, growing to 1 or 2 centimeters in diameter after several years of growth. A biopsy and an examination of suspicious skin lesions may show basal cell carcinoma.