Skin cancer is a malignant growth on the skin, which can have many causes, including repeated severe sunburn or long-term exposure to the sun. Skin cancer generally develops in the epidermis, the outermost layer of skin, so a tumor is usually clearly visible. This makes most skin cancers detectable in the early stages. There are three common types of skin cancer each of which are named after the type of skin cell.
The most common types are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) which may be locally disfiguring but unlikely to spread to other parts of the body. The most dangerous type is malignant melanoma, which can be fatal if not treated early, but forms only a small proportion of all skin cancers. Other types of skin cancers are:
- Dermatofibrosarcoma protuberans
- Merkel cell carcinoma
- Kaposi's sarcoma
Skin cancer is an increasingly common condition, in part attributed to increased exposure to ultraviolet radiation. The increased exposure is mainly due to the recent popularity of sun tanning (sun bathing). Lighter-skinned individuals are more vulnerable. In the United States, about one out of every three new cancers arises from skin. Skin cancers are often curable. Barriers which reduce UV exposure are effective in preventing skin cancers (clothes, hats, creams, lotions).
signs and symptoms
There are a variety of different skin cancer symptoms. These include sores or changes in the skin that do not heal, ulcers in the skin, discoloring in parts of the skin, and changes in existing moles.
Basal cell carcinoma usually looks like a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders. Sometimes small blood vessels can be seen within the tumor. Crusting and bleeding in the center of the tumour frequently develops. It is often mistaken for a sore that does not heal.
Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass.
Most melanomas are brown to black-looking lesions. Signs that might indicate a malignant melanoma include change in size, shape, color or elevation of a mole. The appearance of a new mole during adulthood, or new pain, itching, ulceration or bleeding of an existing mole should be checked.
prognosis and treatment
Minor surface skin cancers are readily treatable by simple surgery, but if the cancer is allowed to grow then it will penetrate through the layers of skin and affect the lymphatic system. It may also metastasize and spread to other parts of the body. Skin cancers which are aggressive, recurrent, or located on "high risk sites" of the body (central face, scalp, ears, genitalia) may require more advanced surgical approaches such as Mohs' micrographic surgery to achieve high cure rates.
more informationThe Skin Cancer Foundation
Skin Cancer Guide
American Cancer Society
Canadian Cancer Society