Skin Cancers

Skin Cancer Types

The cells of most parts of the body are continually dying and being replaced by new ones, the new cells being formed by division of existing ones. This process of division and growth is normally well controlled: in adults so that new cells replace dying ones; in children so that slightly more new cells are formed than are needed to replace dying ones, so that the body grows.

Sometimes the growth of a group of cells can get out of control, usually through damage to the DNA of the cells concerned. The excess of new cells forms a lump, or tumour. Most tumours are benign, and stay in their original location. Some, however, are malignant and spread into surrounding tissue and to other parts of the body. It is these malignant tumours that are called cancers.

Cancers in the skin can be of three main types (there are also a number of other, much rarer types), depending on which cells are forming the tumour:

  • Basal Cell Carcinoma (BCC). This is the most common form of skin cancer, accounting for over 75% of skin cancers in the UK. It is a cancer of the basal cells, the cells in the bottom layers of the epidermis. This type of cancer is slow growing and almost never spreads to other parts of the body. It is easily treated by surgical removal. If left untreated, however, it can develop into a nasty ‘rodent’ ulcer.
  • Squamous Cell Carcinoma (SCC). This is the second most common form of skin cancer, accounting for about 20% of skin cancers in the UK. This is a cancer of the squamous cells, the cells of the outermost layers of the epidermis. It is also slow growing but can sometimes spread to other parts of the body if left untreated for a long time, and can therefore have more serious consequences. It is also usually easily treated by surgical removal.
  • Melanoma. Sometimes also called malignant melanoma. It is relatively rare, accounting for only about 3% of skin cancers, but it is the most serious form, accounting for about 75% of deaths due to skin cancer. It is a cancer of the melanocytes, the melanin-producing cells of the epidermis. It is generally fairly slow growing, taking several months to develop, but if left untreated it grows deeper into the skin and eventually spreads to other parts of the body through the lymph and blood systems, and can then be fatal. However, if caught sufficiently early, before it has grown more than 1 mm deep, it is usually completely curable by surgical removal.

Because of the significantly different behaviour and seriousness of melanoma cancers compared to the others, skin cancers are often classified as two types: melanoma and non-melanoma.

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