What Happens

Nonmelanoma skin cancer usually develops slowly, invading and destroying nearby tissues. It may take months or years for basal cell or squamous cell carcinomas to develop. Because of this slow growth, skin cancer can often be detected and treated early in its development, increasing the chance for a cure.

Basal cell carcinoma

Basal cell carcinoma can invade normal skin tissue and damage deeper tissues, such as muscles and bones, and affect the appearance of the skin. Basal cell carcinoma very rarely spreads (metastasizes) to other parts of the body.

After you have one basal cell carcinoma, you are more likely to have another one develop in a new place. If basal cell carcinoma comes back at the same place (recurs), it may grow faster and cause more tissue damage.

Squamous cell carcinoma

Squamous cell carcinoma is more invasive than basal cell and can spread from the scalp, ears, eyelid, nose, or lip to other areas of the body. But it rarely spreads (metastasizes) to other parts of the body.

Sometimes a squamous cell carcinoma starts as actinic keratosis, which are small rough spots that grow in sun-damaged skin. Actinic keratosis is not a skin cancer, but it may lead to skin cancer.

What Increases Your Risk

Risk factors for nonmelanoma skin cancer include:

• Sunlight, sun lamps, or tanning beds. These expose you to ultraviolet (UV) radiation.
  • UV radiation affects people of all skin types, but especially those with light skin color, freckles, blond or red hair, and blue or light-colored eyes.
  • Living where you get high levels of UV radiation. People living closer to the equator get more UV radiation. And people who live at higher altitudes, such as in the mountains, get more UV radiation.
• A family history of skin cancer or a personal history of skin cancer. Or other things that affect your skin, such as:
  • Inherited genetic disorders, such as xeroderma pigmentosum.
  • A history of severe sunburns, especially during childhood.
  • Scars from severe burns or inflammatory skin conditions.
• Being older than 40.
• Being male. Men develop skin cancer more often than women.
• Smoking.
• Repeated exposure to X-rays, certain chemicals (such as arsenic, coal tar, creosote), and radioactive substances (such as radium).
• Being infected with a certain type of human papillomavirus (HPV).

Basal cell and squamous cell carcinomas can occur in people with dark skin. But these cancers are much more common in people with light skin.

The risk of squamous cell carcinoma is higher in people who have weakened immune systems. This includes people who have had organ transplants and take medicines to prevent rejection of the new organ.