There are two main types of skin cancer: basal cell carcinoma (also called rodent ulcer) and squamous cell carcinoma.

Together these cancers are known as non-melanoma skin cancer. More than 65,000 people in the UK are diagnosed each year with non-melanoma skin cancer.

Basal cell carcinoma, or BCC, is a cancer of the cells at the bottom of the skin's outermost layer, the epidermis. It accounts for more than three-quarters (75%) of all skin cancers in the UK.

Most basal cell carcinomas are slow-growing and almost never spread. However, if they are left untreated they can damage the skin and cause an ulcer, known as a rodent ulcer. A small number of rodent ulcers may come back on the same area of skin after treatment: this is known as a local recurrence.

Squamous cell carcinoma, or SCC, is a cancer of the outermost cells of the skin. It is the second most common type of skin cancer in the UK. One in five skin cancers (20%) are this type.

If it is left untreated for a long time, squamous cell carcinoma can spread to other parts of the body. However, most people treated for squamous cell carcinoma are completely cured with simple treatment.

There are a number of rare types of non-melanoma skin cancer:

• Merkel cell
• Kaposi's sarcoma
• Cutaneous T-cell lymphoma of the skin
• Sarcoma

Together these rare types make up less than one in a hundred (1%) of all skin cancers in the UK.

Another, less common, type of skin cancer is called malignant melanoma. About 7000 people in the UK are diagnosed with malignant melanoma each year. Melanoma behaves differently to basal cell and squamous cell carcinomas.