Skin cancers are cancers that arise from the skin.Skin cancers develop when abnormal cells invade or spread to other parts of the body. There are three main types: basal cell cancer (BCC), squamous cell cancer (SCC) and melanoma. The first two are known as non-melanoma skin cancer (NMSC). Basal cell cancer grows slowly and can damage the tissue around it. Skin cancer often appears as a painless raised area of skin that may be shiny with small blood vessels running over it, or may appear as a raised area with an ulcer. Squamous cell cancer is more likely to spread. It usually appears as a hard lump with a scaly top, but may also form an ulcer. Melanomas are the most aggressive. Signs include a mole that has changed in size, shape, color, has irregular edges, more than one color, is itchy, or sometimes bleeds.
Studies show that greater than 90% of all skin cancer is caused by exposure to ultraviolet radiation from the sun. This exposure increases the risk of all three main types of skin cancer. Exposure has increased partly due to a thinner ozone layer. In addition, tanning beds are becoming another common source of ultraviolet radiation.
Melanomas and basal cell cancers exposure during childhood is particularly harmful. For squamous cell cancers, total exposure, irrespective of when it occurs, is more important. Between 20% and 30% of melanomas develop from moles. People with light skin are at higher risk as are those with poor immune function. Diagnosis is by biopsy.
Skin cancer is the most common form of cancer, globally accounting for at least 40% of cases. It is especially common among people with light skin.