Skin cancer is the most common of all cancers, accounting for as much as half of all cancer diagnoses, according to the American Cancer Society (ACS). Skin cancer is divided into two main categories – melanoma and non-melanoma.

Melanoma is a malignant skin cancer that originates in melanocytes, the cells that produce the skin’s pigment (melanin). Like all cancers, melanoma results from unrepaired damage to DNA, genetic material that is present in every cell.

Melanoma is the least common of the two types of skin cancer, accounting for about 4 percent of all skin cancer cases. However, it is the most deadly form of skin cancer and is responsible for about 75 percent of skin cancer–related deaths each year, according to the Occupational Safety and Health Administration (OSHA). It can spread to almost every organ or tissue in the body. Untreated, melanoma can cause death within a year of diagnosis.

However, melanoma is highly curable when detected and treated early. Patients can learn to recognize the warning signs, which include a darkening and enlarging of an existing mole or an irregular and raised shape. Moles that change color, itch or become crusted can also indicate melanoma.

Melanoma is strongly associated with excessive exposure to ultraviolet radiation (UV), which can come from sunlight or tanning booths and beds. In the United States, the number of diagnosed cases of melanoma is increasing despite warnings about the harmful effects of the sun.

It should be remembered that most moles do not signal melanoma. Some types of benign skin growths may appear similar to melanoma. 

Nevertheless, patients should bring any suspicious mole to the attention of a physician, who is trained to recognize melanomas. Although melanoma is highly treatable, the survival rate drops drastically after it has spread to nearby or, more importantly, distant sites.

Not all skin cancers are melanomas. Melanoma is most commonly diagnosed by physical examination and biopsy. When caught early, melanoma is often treated by surgically removing the tumor. If the cancer has spread, then chemotherapy and radiation therapy may become necessary as treatment.