Font Size

Skin Cancer

Skin Cancer Facts

The skin is the largest organ in the body. Skin cancer is the most common of all human cancers. Some form of skin cancer is diagnosed in more than 3 million people in the United States each year.

Cancer occurs when normal cells undergo a transformation during which they grow abnormally and multiply without normal controls.

  • As the cells multiply, they form a mass called a tumor. Tumors of the skin are often referred to as skin lesions.
  • Tumors are said to be cancerous only if they are composed of malignant cells. This means that they encroach on and invade neighboring tissues because of their uncontrolled growth.
  • Tumors may also travel to remote organs via the bloodstream or lymphatic system.
  • This process of invading and spreading to other organs is called metastasis.
  • Tumors overwhelm surrounding tissues by invading their space and taking the oxygen and nutrients the normal cells need to survive and function.

Skin cancers are of three major types: basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.

  • The vast majority of skin cancers are BCCs or SCCs. While malignant, these are unlikely to spread to other parts of the body. They may be locally disfiguring if not treated early.
  • A small but significant number of skin cancers are malignant melanomas. Malignant melanoma is a highly aggressive cancer that tends to metastasize relatively early and aggressively, thereby spreading to other parts of the body. These cancers may be fatal if not found and treated early.

Like many cancers, skin cancers start as precancerous lesions. These precancerous lesions are changes in skin that are not cancer but could become cancer over time. Medical professionals often refer to these changes as dysplasia. Some specific dysplastic changes that occur in skin are as follows:

Moles (nevi) are simply growths on the skin. They are very common. Very few moles become cancer.

  • Most people have 10-40 moles on their body.
  • Moles can be flat or raised; some begin as flat and become raised over time.
  • The surface is usually smooth.
  • Moles are round or oval and no larger than ¼-inch across.
  • Moles are usually pink, tan, brown, or the same color as the skin. Other colors are sometimes noted.
  • An individual's moles usually look pretty much alike. A mole that looks different from the others should be examined by your healthcare professional.

Dysplastic nevi are not cancer, but they can become cancer.

  • People with dysplastic nevi often have a lot of them, perhaps as many as 100 or more.
  • People with many dysplastic nevi are more likely to develop melanoma, either within an existing nevus or on an area of normal-appearing skin.
  • Dysplastic nevi are usually irregular in shape, with notched or fading borders.
  • Dysplastic nevi may be flat or raised, and the surface may be smooth or rough ("pebbly").
  • Dysplastic nevi are often large, at least ¼-inch across or even larger.
  • Dysplastic nevi are typically of mixed color, including pink, red, tan, and brown.

Recent studies demonstrate that the number of skin cancer cases in the United States is growing at an alarming rate. Fortunately, increased awareness on the part of Americans and their healthcare professional has resulted in earlier diagnosis and improved outcomes.

Last Reviewed 1/4/2018
Medical Author:

Must Read Articles Related to Skin Cancer

Common Health Tests
Common Health Tests Common health tests may be performed in your doctor's office or even in the pharmacy. Regular health checks and screening for certain diseases and conditions ha...learn more >>
Mole Removal
Mole Removal Moles may be removed using exc...learn more >>

Patient Comments & Reviews

The eMedicineHealth doctors ask about Skin Cancer:

Skin Cancer - Describe Your Experience

Please describe your experience with skin cancer.

Skin cancer - Signs and Symptoms

What signs and symptoms did you experience with your skin cancer?

Skin Cancer - Treatment

What was the treatment for your skin cancer?

Patient test for skin cancer

Skin cancer, Nonmelanoma

What is nonmelanoma skin cancer?

Skin cancer is the abnormal growth of cells in the skin. It is the most common type of cancer. It is almost always cured when it is found early and treated. So it is important to see your doctor if you have changes in your skin.

Most skin cancers are the nonmelanoma type. There are two main types of nonmelanoma skin cancer: basal cell carcinoma and squamous cell carcinoma.


Read What Your Physician is Reading on Medscape

Skin Cancer: Melanoma »

Despite recent declines in the incidence and mortality of cancer overall, the incidence of cutaneous melanoma continues to escalate.

Read More on Medscape Reference »

Medical Dictionary