Skin cancers (neoplasms) are named after the type of skin cell from which they arise. Basal cell cancer originates from the lowest
layer of the epidermis, and is the most common but least dangerous skin cancer. Squamous cell cancer originates from the middle layer,
and is less common but more likely to spread and, if untreated, become fatal. Melanoma, which originates in the pigment-producing cells
(melanocytes), is the least common, but most aggressive, most likely to spread and, if untreated, become fatal.
Most cases are caused by over-exposure to UV rays from the sun or sunbeds
There are three main types of skin cancer: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma.
Basal cell carcinomas are present on sun-exposed areas of the skin, especially the face. They rarely metastasize and rarely cause death.
They are easily treated with surgery or radiation. Squamous cell carcinomas (SCC) are common, but much less common than basal cell cancers.
They metastasize more frequently than BCCs. Even then, the metastasis rate is quite low, with the exception of SCC of the lip, ear, and in
immunosuppressed patients. Melanomas are the least frequent of the 3 common skin cancers. They frequently metastasize, and could potentially
cause death once they spread.
Less common skin cancers include: Dermatofibrosarcoma protuberans, Merkel cell carcinoma, Kaposi’s sarcoma, keratoacanthoma, spindle cell
tumors, sebaceous carcinomas, microcystic adnexal carcinoma, Pagets’s disease of the breast, atypical fibroxanthoma, leimyosarcoma, and angiosarcoma.
The BCC and the SCCs often carry a UV-signature mutation indicating that these cancers are caused by UV-B radiation via the direct DNA damage.
However the malignant melanoma is predominantly caused by UV-A radiation via the indirect DNA damage.The indirect DNA damage is caused by free
radicals and reactive oxygen species. Research indicates that the absorption of three sunscreen ingredients into the skin, combined with a
60-minute exposure to UV, leads to an increase of free radicals in the skin, if applied in too little quantities and too infrequently. However,
the researchers add that newer creams often do not contain these specific compounds, and that the combination of other ingredients tends to retain
the compounds on the surface of the skin. They also add the frequent re-application reduces the risk of radical formation.