Skin cancers represent a group of tumours originating from one cell type in the skin and are clinically diverse. In normal circumstances cell division is regulated through a cycle and any errors in the division process are corrected and faulty cells eliminated. In cancers the cell division process becomes unregulated and uncontrolled with as a result an overgrowth of abnormal cells leading to malfunction.
Risk factors for developing skin cancer include excessive ultraviolet sun exposure, artificial tanning and genetic predisposition. Fair skinned individuals are at a higher risk of developing skin cancers and in particular those types that are related to sun exposure.
The commonest type of skin cancer is called basal cell carcinoma and has the best prognostic outcome as it tends to cause local tissue destruction but very rarely spreads to other sites or organs and therefore is the least aggressive type. Basal cell carcinoma has several subtypes with the superficial subtype being the least aggressive and the sclerotic subtype being the most destructive.
Squamous cell carcinoma, like basal cell carcinoma arises from an abnormal cell division of the keratinocytes which is the principle cell in the upper layer of the skin called the epidermis. Squamous cell carcinoma however can behave biologically aggressive and spread to other sites or organs and if untreated can cause mortality. Sun exposure is a key factor and this type of skin cancer has a high prevalence among patients who are heavily immunosuppressed such as transplant patients.
Melanoma is the most aggressive type of skin cancer and originates from the melanocytes which is the pigment producing cell. Melanomas that are detected early have a much better prognosis than late diagnosed cases as this type of skin cancers has a high chance of spreading to other sites and organs with subsequent fatal outcomes. It is therefore essential that this type of skin cancer is detected as early as possible. Risk factors include sunburns, artificial tanning, a personal or family history of melanoma and the presence of more than 50 moles, particularly in a fair skinned individual.
The treatment of skin cancer depends on the type with surgical excision being the commonest method of treatment. Other treatment modalities include Mohs surgery, cryotherapy, curettage and topical anti-cancer cream called imiquimod.
Professor Firas Al-Niaimi has published many articles on skin cancers and these can be found in the publications section of the website.
How many different types of skin cancer are there?
There are three types of skin cancer: malignant melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Malignant melanomas are the most dangerous type of skin cancer and appear as a skin cancer mole; the signs of skin cancer can be identified by the ABCD method:
Asymmetry – The dark, pigmented area appears wonky in appearance.
Border – the edges may be uneven or appear broken.
Colour – the colour may be inconsistent.
Diameter – most melanomas are at least 6 mm across.
Non-melanoma skin cancers include SCC and BCC types which are less dangerous, although both carcinomas can become painful if left untreated for a long time.