Actinic Keratosis and Other Precancers

THE MOST COMMON PRECANCER :  More Than Ten Million

This figure is generally accepted as the best current estimate of the number of Americans with actinic keratosis (AK). People with a fair complexion, blond or red hair, and blue, green or grey eyes (Identify Your Skin Type) have a high likelihood of developing one or more of these common precancers if they spend time in the sun and live long enough. Location makes a difference: The closer to the equator you live, the more likely you are to have actinic keratoses.

The incidence is slightly higher in men, because they tend to spend more time in the sun and use less sun protection than women do. African-
Americans, Hispanics, Asians and others with darker skin are not as susceptible as Caucasians (Skin Cancer and Skin of Color).

Is There Cause for Concern?

Actinic keratosis can be the first step leading to squamous cell carcinoma and is therefore known as a “precancer.” Although the vast majority of actinic keratoses remain benign, some studies report that up to ten percent may advance to squamous cell carcinoma. This percentage does not sound very large, but it has a large impact. When it comes to squamous cell carcinomas, 40-60 percent begin as untreated actinic keratoses and may advance to invade the surrounding tissues. About 2 to 10 percent of these squamous cell carcinomas spread to the internal organs and are life-threatening.

Another form of actinic keratosis, actinic cheilitis, develops on the lips and may evolve into squamous cell carcinoma.

The more keratoses you have, the greater the chance that one or more may turn into skin cancer. In fact, some scientists interpret actinic keratosis as the earliest form of squamous cell carcinoma.

What Is Actinic Keratosis?

An actinic keratosis, also known as a solar keratosis, is a scaly or crusty growth (lesion). It most often appears on the bald scalp, face, ears, lips,
backs of the hands and forearms, shoulders, neck or any other areas of the body frequently exposed to the sun. You’ll most often see the plural,
“keratoses,” because there is seldom just one.

In the beginning, actinic keratoses are frequently so small that they are recognized by touch rather than sight. It feels as if you were running a finger over sandpaper. There are many times the number of invisible (subclinical) lesions as visible ones on the skin surface.

Most often, actinic keratoses develop slowly and reach a size from an eighth to a quarter of an inch. Early on, they may disappear only to reappear later. Most become red, but some will be light or dark tan, pink, red, a combination of these, or the same color as your skin. Occasionally they itch or produce a pricking or tender sensation. They can also become inflamed and surrounded by redness. In rare instances, actinic keratoses can even bleed.

If you have actinic keratoses, it indicates that you have sustained sun damage and could develop any kind of skin cancer – not just squamous cell carcinoma.

Actinic keratosis on the back of the hand. These precancers commonly occur on the face and the back of the hands.

A closeup shows elevation, roughness, and crusting. Some keratoses, like this one, are quite discrete and difficult to distinguish clinically from squamous cell carcinoma.

How to Recognize Actinic Keratosis

Examples of typical actinic keratoses are shown here, so examine your skin regularly for lesions that look like them. But it’s not always that simple:

Many actinic keratoses have quite a different appearance, so if you find any unusual or changing growth, be suspicious and see your doctor promptly.

Numerous actinic keratoses can reveale chronic sun damage. They are elevated, rough in texture, and resemble warts.

Two typical keratoses on rim of ear. The top lesion is crusted, the lower one rough in appearance.

While most keratoses have a fine sandpapery roughness, others such as this lesion have an obviously scaly, crusty surface.

Chronic sun exposure is the cause of almost all actinic keratoses. Sun damage to the skin is cumulative, so even a brief period in the sun adds to the lifetime total. Cloudy days aren’t safe either, because 70-80 percent of solar ultraviolet (UV) rays can pass through clouds. These harmful rays can also bounce off sand, snow and other reflective surfaces, giving you extra exposure.

The ultraviolet radiation given off by the lamps in a tanning salon can be even more dangerous than the sun, so dermatologists warn against indoor tanning.

Occasionally, actinic keratoses may be caused by extensive exposure to X-rays or a number of industrial chemicals.

What Age Has to Do with It

Because the total amount of time spent in the sun adds up year by year, older people are most likely to develop actinic keratoses. However, nowadays, some individuals in their 20s are affected. Still, actinic keratoses become much more common in people over the age of 50. Some experts believe almost everyone over 80 has actinic keratoses.

Also, individuals whose immune defenses are weakened by cancer chemotherapy, AIDS, organ transplantation or excessive UV exposure are less able to fight off the effects of the radiation and thus more likely to develop actinic keratoses.

A PUBLICATION OF THE SKIN CANCER FOUNDATION
For more information or to order this article as a brochure, please contact:
The Skin Cancer Foundation
149 Madison Ave., Suite 901,
New York, NY 10016
© 2008

Photos courtesy of:
Pearon G. Lang, Jr., MD, and
MSKCC Dept. of Dermatology
Photos courtesy of:
Pearon G. Lang, Jr., MD, and
Memorial Sloan Kettering Cancer Center
Deptartment of Dermatology