Incidence and Risk Factors

The main protection of the skin against sunlight damage is the production of pigment. In Afro-Caribbean and Asian races, basal cell tumours are therefore rare. In pale races they are common. The most susceptible are people of Celtic origin because they have little pigment and fair skins. Many people have a history of damage or injury to that part of the skin where the basal cell growth later develops. The exact importance of such injury is unknown

The incidence of skin cancer has increased greatly in recent years, due in part to greater exposure to UV radiation from the sun. Also, other risks include a genetic predisposition -- basal cell carcinomas are more common in those who have light coloured skin, blue or green eyes, blond or red hair -- and overexposure to X-rays or other forms of radiation.

This cancer usually remains localised to the area of the face or scalp, where it has developed, and almost never spreads to distant parts of the body. However it may continue to grow and invade nearby tissues and structures, including the nerves, bones, and brain. The tumour may begin very small, growing to 1 or 2 centimetres in diameter after several years of growth.