What is Skin Cancer?
Skin cancer is the most common form of cancer people get in the United States. Read an overview about the causes and types of skin cancer.

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Skin cancer is the most common form of cancer in the United States. More than two million people are diagnosed with skin cancer annually. According to the Skin Cancer Foundation (SCF), one in five Americans will develop skin cancer in the course of his or her lifetime. Each year, there are more new cases of skin cancer than breast, prostate, lung, and colon cancers combined. If left untreated, the disease can be deadly, but if skin cancer is caught while still in its early stages, the outlook is usually positive.

Skin cancer is primarily caused by ultraviolet (UV) radiation from sun exposure or from indoor tanning, though some people can develop skin cancer without being exposed to the sun’s harmful rays. UV radiation damages skin cells, which can cause abnormalities that lead to skin cancer. People of all skin tones can develop the disease, but those with fair skin are at a higher risk of skin cancer than people with darker skin.

Skin cancer can occur at any age, but it doesn’t affect men and women equally. Up until age 39, women are almost twice as likely to develop melanoma as men, according to the SCF. Starting at age 40, the number of men with melanoma exceeds the number of cases in women. The incidence goes up every decade.

Types of Skin Cancer

There are several different types of skin cancer. The disease is classified according to the types of skin cells involved. Types of skin cancer include:

Precancerous Lesions—Actinic Keratosis

Actinic keratosis is considered a “precancer,” meaning it can be the first step that leads to a type of skin cancer. Most actinic keratoses are benign, but some studies show that up to 10 percent may progress to squamous cell carcinoma. Actinic keratosis affects more than 58 million Americans. About 65 percent of all squamous cell carcinomas come from lesions that previously were diagnosed as actinic keratoses. Actinic keratosis is also sometimes known as solar keratosis.

Basal Cell Carcinoma

Basal cell carcinoma stems from abnormal growth of the cells in the most superficial layer of the skin, known as the epidermis. This is the most common type of skin cancer with an estimated 2.8 million are diagnosed annually in the U.S. However, it is rarely fatal but can occasionally metastasize and needs to be addressed by a physician with experience treating skin cancers.

Squamous Cell Carcinoma

Squamous cell carcinoma involves cancerous changes in the cells located in the middle layer of the epidermis, known as squamous cells. It’s the second most common form of skin cancer, with an estimated 700,000 cases diagnosed each year in the U.S. Untreated squamous cell carcinomas can lead to severe complications; on the other hand, when treated early, they rarely cause any problems.


Melanoma is the most dangerous type of skin cancer. It forms in the melanocytes, which are the cells that produce the skin’s pigment (called melanin). Melanoma is less common than basal or squamous or cell carcinoma, but it’s more deadly. It accounts for less than five percent of skin cancer cases, but it causes more than 75 percent of skin cancer deaths. Melanoma is the leading cause of death from skin disease, and young adults are particularly vulnerable. Melanoma is the most common cancer in young adults ages 25 to 29 years old and the second most common cancer in those ages 15 to 29 years old.

Melanomas typically appear as a change in an existing mole or a new, strange-looking growth on your skin. They are most often found on body parts that are exposed to the sun’s UV rays on a regular basis. However, they can appear anywhere, even in your eyes or in your intestines. If you experience any change to your skin, you should have a doctor examine it; the earlier melanoma is caught, the better the outlook.

Other Types of Skin Cancer

Other, rare types of skin cancer include:

  • Kaposi sarcoma
  • Merkel cell carcinoma
  • Sebaceous gland carcinoma
Written by: the Healthline Editorial Team
Edited by:
Medically Reviewed by: Jennifer Monti, MD
Published: Apr 25, 2011
Published By: Healthline Networks, Inc.
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