What You Should Know About This Common Precancer
You have surely seen an actinic keratosis. The name may be unfamiliar, but the appearance is commonplace. Anyone who spends time in the sun runs a high risk of developing one or more.
What is it?
An actinic keratosis (AK), also known as a solar keratosis, is a small crusty, scaly, or crumbly bump or horn that arises on the skin surface. The base may be light or dark, tan, pink, red, or a combination of these or the same color as your skin. The scale or crust is horny, dry, and rough, and is often recognized by touch rather than sight. Occasionally it itches or produces a pricking or tender sensation. It can also become inflamed and surrounded by redness. In rare instances, actinic keratoses can bleed. The skin abnormality or lesion develops slowly and usually reaches a size from an eighth to a quarter of an inch (2 mm to 4 mm) but can sometimes be as large as one inch. Early on, it may disappear only to reappear later. You will often see several AK’s at a time. An AK is most likely to appear on the face, lips, ears, scalp, neck, backs of the hands and forearms, shoulders and back. The parts of the body most often exposed to sunshine. The growths may be flat and pink or raised and rough.
Why is it dangerous?
AK can be the first step in the development of skin cancer. It is thus a precursor of cancer or a pre-cancer. If treated early, almost all AK’s can be eliminated without becoming skin cancers. But untreated, about two to five percent may progress to squamous cell carcinoma (SCC), the second most common form of skin cancer. In fact, some scientists now believe that AK is the earliest form of SCC. Although SCC’s are usually not life-threatening when detected and treated in the early stages, they can grow large and invade the surrounding tissues. On rare occasions, they metastasize or spread to the internal organs. Another form of AK, actinic cheilitis, develops on the lips and may evolve into a type of SCC that can spread rapidly to other parts of the body. If you have AK’s, it indicates that you have sustained sun damage and could develop any kind of skin cancer not just squamous cell carcinoma. The more keratoses that you have, the greater the chance that one or more may turn into skin cancer. People may also have up to 10 times as many invisible lesions as visible, surface lesions. Actinic Keratosis is skin cancer’s warning signal. Heed that signal.
What does it look like?
AK’s are rough, scaly, slightly raised growths that range in color from brown to red and may be up to one inch in diameter It may feel like fine sand paper when generally rubbed. Examine your skin regularly for any lesions that look like them. If you ever spot these or any other suspicious or changing growths, see your doctor promptly.
What is the cause?
Chronic sun exposure is the cause of almost all AK’s. Sun damage to the skin accumulates over time, so that even a brief exposure adds to the lifetime total. The likelihood of developing AK’s is highest in regions near the equator. However, regardless of climate, everyone is exposed to the sun. About 80 percent of solar ultraviolet (UV) rays can pass through clouds. These rays can also bounce off sand, snow, and other reflective surfaces, giving you extra exposure. AK’s can appear on skin that has been frequently exposed to artificial sources of UV light (such as tanning devices). More rarely, they may be caused by extensive exposure to X-rays or specific industrial chemicals.
Who is at greatest risk?
People who have fair skin, blonde or red hair, and/or blue, green, or gray eyes are at greatest risk. Because their skin has little protective pigment, they are most susceptible to sunburn. But even darker-skinned people can develop AK’s if exposed to the sun without protection. Individuals whose immune systems are weakened as a result of cancer chemotherapy, AIDS, or organ transplantation are also at higher risk.
How common is it?
AK is the most common type of precancerous skin lesion. Older people are more likely than younger ones to develop these lesions, because cumulative sun exposure increases with the years. Some experts believe that the majority of people who live to the age of 80 will have AK’s. However, a considerable amount of our lifetime sun exposure occurs before age 20. Thus, AK’s also appear in people in their early twenties who have spent too much time in the sun with little or no protection.
How is it treated?
There are many effective methods for eliminating AK’s. All cause a certain amount of reddening, and some may cause scarring, while other approaches are less likely to do so. You and your doctor should decide together the best course of treatment, based on the nature of the lesion and your age and health.
The most common treatment for AK is cryosurgery. It is especially effective when a limited number of lesions exist. Liquid nitrogen is applied to the growths with a spray device or cotton-tipped applicator to freeze them. They subsequently shrink or become crusted and fall off, without requiring any cutting or anesthesia. Some temporary redness and swelling may occur after treatment, and in dark-skinned patients, some pigment may be lost.
Curettage and Desiccation
This is a valuable procedure for lesions suspected to be early cancers. To test for malignancy, the physician takes a biopsy specimen, either by shaving off the top of the lesion with a scalpel or scraping it off with a curette. Then the curette is used to remove the base of the lesion. Bleeding is stopped with an electrocautery needle. Local anesthesia is required.
Medicated creams and solutions are especially useful in removing both visible and invisible AK’s when the lesions are numerous. The patient applies the medication according to a schedule worked out by the physician. The doctor will also regularly check progress. After treatment, some discomfort may result from skin breakdown, but the risk of scarring is minimal.
5-fluorouracil (5-FU) cream or solution, in concentrations from 0.5 to 5 percent, is the most widely used topical treatment for AK. It works well on the face, ears, and neck. Some redness, swelling, and crusting may occur. Another preparation, Imiquimod cream, is used for multiple keratoses. It causes cells to produce interferon, a chemical that destroys cancerous and precancerous cells. An alternative treatment, a gel combining, hyaluronic acid and the anti-inflammatory drug diclofenac, also may prove effective.
This method makes use of trichloroacetic acid (TCA) or a similar agent applied directly to the skin. The top skin layers slough off, usually replaced within seven days by new epidermis (the skin’s outermost layer). This technique requires local anesthesia and can cause temporary discoloration and irritation.
A carbon dioxide or erbium YAG laser is focused onto the lesion, removing epidermis and different amounts of deeper skin. This finely controlled treatment is an option for lesions in small or narrow areas; it can be effective for keratoses on the face and scalp, as well as actinic cheilitis on the lips. Laser surgery is useful for people with bleeding disorders and is also used as a secondary therapy when other techniques are unsuccessful. However, local anesthesia is usually necessary, and some scarring and pigment loss can occur.
Photodynamic Therapy (PDT)
PDT may be used to treat lesions on the face and scalp. Topical 5-aminolevulinic acid (5-ALA) is applied to the lesions by the physician. Within the next 24 hours, the medicated areas are exposed to strong light, which activates the 5-ALA. The treatment selectively destroys actinic keratoses, causing little damage to surrounding normal skin, although some swelling and redness often occur.