Aging & Health A to Z

Skin Cancer

Causes & Symptoms

Most skin cancers, particularly basal cell and squamous cell types, are caused by exposure to sunlight. The ultraviolet rays of the sun—particularly UVB and UVA wavelengths—cause DNA damage in the cells. This may cause the cells to start dividing in an uncontrolled way. The resulting lesions (patches of diseased or damaged skin) usually occur on areas of the skin that have received most sun exposure. These are typically the face, the back of the hands, and the arms. Your chances of having a skin cancer increases with age and lifetime sun exposure.

Besides sunlight, being in contact with certain chemicals or taking medications that suppress your immune system can increase your risk of getting skin cancer.

Risk Factors

The following risk factors may increase your chance of developing skin cancer:

• Light skin color
• Red or blond hair
• Long-term sun exposure
• Having had severe, blistering sunburns in childhood
• Increasing age
• Certain genetic patterns that may run in families
• Exposure to specific chemicals (such as arsenic) or radiation
• Having a compromised immune system.
• Presence of certain types of skin abnormalities such as actinic keratoses (rough, red scaly patches).
• Presence of wounds or scars that will not heal
• Cigarette smoking.

The risk of the cancer spreading or invading other tissues increases with certain features such as:

• Greater tumor size
• Certain types of cells (melanomas are highly likely to spread, squamous cell cancers rarely do but can, and basal cell cancers are least likely to spread to internal organs)
• Depth of the tumor in the skin (deeper tumors are more likely to spread)
• Location of the tumor (squamous tumors on lip or ear may be more aggressive).

Symptoms and Warning Signs 

The following signs—often painless, but sometimes with some tenderness—may be early indicators that you have skin cancer or that a skin cancer may develop in the future:

• Waxy, pearly pimple on the skin covered with splotchy enlarged blood vessels and with a “rolled” border
• A scar-like abnormality
• Reddish patch (flat or slightly raised)
• Rough, scaly, or crusted areas
• Thick, horny growths
• Wounds that ooze and do not heal after a reasonable time
• Patch or mole that seems newly pigmented (darkened)
• Changes in color, size, surface, or borders of a mole.

 Warning signs for melanoma are summarized by the mnemonic “ABCD” which stands for

• Asymmetry (uneven or irregular shape)
• Borders (uneven)
• Color (tan, brown, gray, black or blue-black – may be quite varied)
• Diameter (more than about a quarter of an inch).

Older adults over 65 years of age should also check for dark brown or black patches on the palms of the hands, soles of the feet, or on the nail beds of the fingers or toes. These may be melanomas. 

Updated: March 2012
Posted:  March 2012