Overview

What is cancer?

Cancer is the uncontrolled growth of cells in an organ, such as the skin, lung or colon. Cancer cells often grow together to form a tumor. The malignant tumor of skin cancer often appears on the surface as a pigmented mole or a small rash. Skin cancer, especially melanoma, is a dangerous disease when cancer cells invade surrounding tissue and spread (metastasize) through the bloodstream or lymphatic system to distant parts of the body. Early detection before the cancer metastasizes provides the best chance of cure.

What is skin cancer?

Skin is the largest organ of the body and is made of several cell types, each of which can give rise to a different form of cancer. There are a variety of effective treatments for skin cancer, especially if discovered early, when still localized. Early detection depends on knowing your risk for skin cancer and doing regular self-exams. Avoiding the sun's harmful ultraviolet radiation can help prevent skin cancer.

Skin cancers are divided into two main groups: non-melanoma skin cancer and melanoma.

Non-melanoma skin cancer (NMSC)

The two major forms of NMSC are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). NMSCs are common compared to malignant melanoma. They arise from skin cells near the surface of the skin.

BCC rarely metastasizes. When it does, the cancer cells do not grow effectively. However, if untreated, the primary BCC tumor can become locally aggressive and destructive. SCC usually develops on the face or other sun-exposed regions as a precancerous lesion. Both BCC and SCC are slow-growing cancers. SCC, if untreated, has a much greater tendency to metastasize than BCC.

Melanoma

The most dangerous form of skin cancer is malignant melanoma, which arises from pigment-producing cells (melanocytes) just below the epidermis. There will be an estimated 7,910 deaths from melanoma in 2006.

More on Skin Cancer

In the Encyclopedia:

This article was reviewed and updated June 2007.