Three types of skin cancer are the most common: •Basal cell carcinoma is a slow-growing cancer that seldom spreads to other parts of the body. Basal cells, which are round, form the layer just underneath the epidermis, or outer layer of the skin.
•Squamous cell carcinoma spreads more often than basal cell carcinoma, but still is considered rare. Squamous cells, which are flat, make up most of the epidermis.
•Melanoma is the most serious type of skin cancer. It occurs when melanocytes, the pigment cells in the lower part of the epidermis, become malignant, meaning that they start dividing uncontrollably. If melanoma spreads to the lymph nodes it may also reach other parts of the body, such as the liver, lungs or brain. In such cases, the disease is called metastatic melanoma.
In the UK between 2009 and 2011, an average of 27% of cases were diagnosed in those aged under 50 years, and an average of 24% of cases were diagnosed in the 75s.