Aging Skin: Blemishes and Nonmelanoma Skin Cancers
DescriptionAn in-depth report on the diagnosis, treatment, and prevention of age-related skin problems.
Alternative NamesActinic Dermatitis; Actinic Keratoses; Skin Cancer; Sun Protections and Sunscreens
Skin cancer is now more common than all human cancers combined. In one study of people over 50 years, 65% had significant skin problems, including precancerous lesions and skin cancers. In fact, according to the American Cancer Society, more than a million non-melanoma skin cancers are diagnosed every year. Melanoma, although less common than the other two major skin cancers, is the most dangerous.
Risk Factors for Skin Cancers
Sunlight and Ultraviolet Radiation. By far the most significant risk factor for all skin cancer is exposure to UV radiation.
Other Risk Factors. Other factors may increase the risk for specific skin cancers, including the following:
Anyone with risk factors for skin cancers should be vigilant:
Melanoma is the most serious of skin cancers. It is named for the skin cell from which it arises, the melanocyte, which produces pigment, or melanin. As people age, these pigment-forming cells often proliferate, forming harmless moles (called nevi).
Infrequently, however, the cells grow out of control and become melanomas, which are malignant and can be life threatening. Once relatively uncommon, malignant melanoma is increasing at an alarming rate, faster than any other cancer.
When melanoma is confined to the outer layer of skin, it is curable in 90% of cases. But if unchecked it can continue to spread to lymph and blood vessels, which increases the likelihood of its affecting distant sites in the body.
A mnemonic device, ABCD, is used to describe several features that help to distinguish melanomas from noncancerous growths:
Individuals most at risk for melanoma tend to have a fair or freckled complexion, blond hair with blue, green or gray eyes, skin that burns easily, a history of sunburn, especially as a child or teenager, and a family history of melanoma.
Treatment consists of surgery, which can be curable if the cancer has not yet spread to the lymph nodes and to other sites in the body. Several new strategies for combating metastatic melanoma are being explored, including boosting the body's natural immune response to fight the disease.
Basal Cell Carcinomas
Basal cell carcinoma (BCC) is named for the round basal cells located in the lower part of the epidermis (the outermost layer of the skin), from which it arises. It is the most common skin cancer and, like melanoma, has been increasing at a dramatic rate.
Prevalence and Risk Factors. Basal cell carcinoma occurs in 800,000 people every year, and 30% of people, almost exclusively Caucasians, can expect to have basal cell carcinoma, on average, by age 55. Some experts posit that genetic mutations caused by factors other than sunlight may also contribute to basal cell cancer.
Interestingly, a 2001 study reported that people with more wrinkles were less likely to develop basal cell carcinomas, even among high-risk groups. Some experts suggest that people prone to wrinkles may respond to sun exposure with biologic mechanisms that protect against basal cell carcinoma. More research is needed confirm this.
Characteristics. The lesions usually develop later in life in areas that have received the most sun exposure, such as the head, neck and back, and especially the nose. About a third of basal cell carcinomas appear in areas not exposed to the sun.
Basal cell carcinomas (BCCs) are highly variable in appearance:
They are sometimes hard to tell from benign skin conditions. For instance, occasionally they arise in unexposed skin, where they may mimic an ordinary mole, cyst, or pimple. They may be particularly difficult to distinguish from benign cysts when they occur near the eyes.
Outlook. Usually, basal cells are slow growing and they are rarely fatal. Most basal cell carcinomas need not be treated as an emergency, although late treatment can cause disfigurement, so they should be removed as early as possible.
The basal cell carcinomas that are most likely to spread are larger ones (more than 1 centimeter), scar-like BCCs, particularly those located on the cheek, and any BCC on the nose, neck, earlobe, eyelid, or temple.
Some studies are indicating that people with basal cell carcinoma may be at higher risk for second cancers, including melanoma, cancer of the lip, salivary glands, larynx, lung, breast, and kidney and non-Hodgkins lymphoma. Those at higher risk for such cancers appear to be men and anyone diagnosed before 60 with BCC.
Squamous Cell Carcinoma and Bowen's Disease
Characteristics. Squamous cell carcinoma (SCC) develops from keratinocytes, flat, scale-like skin cells that lie under the top layer of the epidermis. The majority of squamous cell carcinomas occur on sun-exposed areas, especially the forehead, temple, ears, neck, and back of the hands. People who have spent considerable time sunbathing may develop them on their lower legs. Their appearance changes with its stage:
Prevalence and Risk Factors. About 160,000 people develop squamous cell carcinomas every year. The incidence of this cancer is increasing.
Sun exposure and sun damage are the greatest risk factors, and the addition of other factors compound the risk:
Outlook and Severity. Prompt treatment is desirable because squamous cell carcinomas are more likely to spread to local lymph nodes than are basal cell carcinomas, the other common skin cancer. Mortality rates for this cancer are very low, although squamous cell cancer still kills between 2,000 and 2,500 Americans each year. The risk for metastases (the spread of cancer to other organs) ranges from 0.5% to 16%, depending on risk factors. Squamous cell carcinomas most likely to spread include the following:
People with squamous cell carcinomas seem to be at higher risk for other cancers, including melanoma itself, lung cancer, non-Hodgkin lymphoma, bladder cancer, leukemia, and testicular and prostate cancer in men and breast cancer in women.
Precancerous Skin Disorders
Actinic (Solar) Keratoses. Actinic (also called solar) keratoses are the most common of all precancerous skin lesions. In fact, evidence now strongly supports the belief that actinic keratoses are actually squamous cell carcinomas in situ (the early stage of SCC). It should be noted, however, that not all actinic keratoses progress to carcinomas. One long-term study in 1999 indicated that the rate of malignant transformation might be about 10% over a 10-year period, while other studies show higher rates of progression to SCC.
Actinic keratoses occur after years of sun exposure and afflict over half of Caucasian persons aged 40 or older who live in hot sunny climates. They occur predominantly on sun-exposed skin such as the face, neck, back of the hands and forearms, upper chest, and upper back. Men may develop keratoses along the rim of the ear.
Actinic keratoses have the following characteristics:
Keratoacanthomas. Keratoacanthomas closely resemble squamous cell carcinomas but they are not malignant. The majority arises in sun-exposed skin, usually on the hands or face. They are typically skin colored or slightly reddish when they first develop but their appearance typically changes:
Most will spontaneously regress within a year but they almost always scar after healing. Also about 25% develop into squamous cell carcinomas, most frequently in older people and in sun-exposed areas. Removal by surgery (sometimes by radiation) is recommended. They may also be treated with 5-fluorouracil, either as a cream (Efudex) or with injections.