April 16, 2007

Skin Cancers


Skin cancer is the most common form of cancer in the United States. The three main types of skin cancer—basal cell carcinoma, squamous cell carcinoma, and melanoma—are caused, at least in part, by long-term sun exposure. Lymphoma can also develop in the skin (see Lymphomas: Introduction). Fair-skinned people are particularly susceptible to developing most forms of skin cancer because they produce less melanin, the protective pigment in the epidermis that filters out ultraviolet (UV) light. However, skin cancer also can develop in dark-skinned people and in people whose skin has not had significant sun exposure. Most skin cancers are curable, especially when treated at an early stage. Therefore, any unusual skin growth that persists for more than a few weeks is best examined by a doctor.

Doctors treat most skin cancers by removing them surgically. Usually, the defect that is left in the skin is small. Larger or more invasive cancer may require removal of a significant amount of skin, which may have to be replaced with a skin graft

Basal Cell Carcinoma
Basal cell carcinoma is a cancer that originates in cells of the epidermis.

Basal cells are found in the lowest layer of the epidermis. Although basal cell carcinoma may not originate in the basal cells, the disease is so named because the cancer cells resemble basal cells. Basal cell carcinoma is the most common human cancer. More than 1 million people develop this type of cancer in the United States each year. Basal cell carcinoma usually develops on skin surfaces that are exposed to sunlight, commonly on the head or neck. The tumors usually begin as small, shiny, firm raised growths (papules) that enlarge very slowly, sometimes so slowly that they go unnoticed as new growths. However, the growth rate varies greatly from tumor to tumor, with some growing as much as ½ inch in a year.

Basal cell carcinomas can vary greatly in their appearance. Some are raised bumps that may break open and form scabs in the center. Some are flat pale or red patches that look somewhat like scars. The border of the cancer is sometimes thickened and pearly white. The cancer may alternately bleed and form a scab and heal, leading a person to falsely think that it is a sore rather than a cancer.

Basal cell carcinomas rarely spread (metastasize) to distant parts of the body. Instead, they invade and slowly destroy surrounding tissues. When basal cell carcinomas grow near the eye, mouth, bone, or brain, the consequences of invasion can be serious. Yet, for most people, the tumors simply grow slowly into the skin.

Diagnosis, Treatment, and Prevention

A doctor often can recognize a basal cell carcinoma simply by looking at it, but a biopsy is the standard procedure for confirming the diagnosis.

A doctor removes the cancer in the office by scraping and burning it with an electric needle (curettage and electrodesiccation) or by cutting it out. A technique called Mohs' microscopically controlled surgery may be required for some basal cell carcinomas that regrow or occur in certain areas, such as around the nose and eyes. Rarely, radiation treatment is used.

Treatment is nearly always successful, and basal cell carcinoma is rarely fatal. However, in almost 25% of people who have been treated successfully, another basal cell carcinoma develops within 5 years. Thus, anyone with one basal cell carcinoma should have yearly skin examinations.

Because basal cell carcinoma is often caused by sun exposure, people can help prevent this cancer by staying out of the sun and using protective clothing and sunscreen. In addition, any skin change that persists for more than a few weeks should be evaluated by a doctor

Kaposi's Sarcoma
Kaposi's sarcoma is a cancer that produces multiple flat pink, brown, or purple patches or bumps on the skin; it is caused by herpesvirus type 8.

Kaposi's sarcoma occurs in several distinct groups of people and acts differently in each group. It occurs in older men, usually of Mediterranean or Jewish heritage; in children and young men from certain parts of Africa; in people receiving immunosuppressants after organ transplantation; and in people with AIDS (which accounts for most of the cases in the United States).


In older men, Kaposi's sarcoma usually appears as a single purple or dark brown spot on the toes or leg. The cancer may grow to several inches or more as a deeply colored, flat or slightly raised area that tends to bleed and break open. Several additional spots may appear on the leg, but the cancer rarely spreads to other parts of the body and is almost never fatal.

In the other groups, Kaposi's sarcoma is more aggressive. Similar appearing spots develop, but they are often multiple and may occur anywhere on the body. Within several months, the spots spread to other parts of the body, often including the mouth, where they cause pain with eating. They may also develop in lymph nodes and internal organs, especially the digestive tract, where they can cause diarrhea and internal bleeding that leads to blood in the stool.

Diagnosis and Treatment

Doctors usually recognize Kaposi's sarcoma by its appearance. A biopsy is usually performed to confirm the diagnosis.

Older men with slow-growing Kaposi's sarcoma in one or two spots may have the tumors removed surgically or by freezing. People with multiple spots usually receive radiation therapy. Some people with very few spots and no other symptoms may choose to receive no treatment unless the condition spreads.

People who have the more aggressive form, but whose immune system is normal, often respond to interferon-alpha or chemotherapy drugs.

In people taking immunosuppressants, the tumors sometimes disappear when immunosuppressants are discontinued. If these drugs must be continued because of the person's underlying condition, however, chemotherapy and radiation therapy are used. However, these treatment methods are less successful than in people with a healthy immune system.

In people with AIDS, treatment with chemotherapy and radiation has not been very successful. The best results are achieved in people whose immune system improves as a result of intensive treatment with AIDS drugs. In general, treating Kaposi's sarcoma does not appear to prolong the lives of people with AIDS.

Melanoma is a cancer that originates in the pigment-producing cells of the skin (melanocytes).

Melanocytes are the pigmented cells in the skin that give skin its distinctive color. Sunlight stimulates melanocytes to produce more melanin (the pigment that darkens the skin) and increases the risk of melanoma.

Melanoma can begin as a new, small, pigmented skin growth on normal skin, most often on sun-exposed areas, or it may develop from preexisting pigmented moles (see Noncancerous Skin Growths: Moles). Sometimes melanoma runs in families. Melanoma readily spreads (metastasizes) to distant parts of the body, where it continues to grow and destroy tissue.

Melanomas can vary in appearance. Some are flat, irregular brown patches containing small black spots. Others are raised brown patches with red, white, black, or blue spots. Sometimes melanoma appears as a firm black or gray lump.

Diagnosis, Treatment, and Prevention

A new mole or changes in a mole—such as enlargement (especially with an irregular border), darkening, inflammation, spotty color changes, bleeding, broken skin, itching, and pain—are warnings of possible melanoma. If these or other findings lead a doctor to suspect melanoma, he performs a biopsy. Growths are usually removed entirely. The tissue is then examined under a microscope to determine whether the growth is a melanoma and, if so, whether all the cancer has been removed.

Most darkly pigmented growths that are sent for biopsy are not melanoma but, rather, simple moles. Nonetheless, it is preferable to remove a harmless mole than to allow a cancer to grow. Some growths are neither simple moles nor melanomas but something in between. These tumors, called dysplastic nevi, or atypical moles, sometimes later turn into melanoma.

The less a melanoma has grown into the skin, the greater the chance that surgery will cure it. Almost 100% of the earliest, most shallow melanomas are cured by surgery. Thus, doctors treat melanomas by cutting them out, taking at least a ½-inch border of skin around the tumor. However, melanomas that have grown deeper than 1/32 inch into the skin are very likely to have spread (metastasized) through the lymphatic and blood vessels. Melanomas that have spread are often fatal.

Chemotherapy is used to treat melanomas that have spread, but few are cured. Some of the people treated live less than 9 months. However, the course of the disease varies greatly and depends in part on the strength of the body's immune defenses. Some people survive in apparent good health for several years despite the spread of the melanoma. New experimental treatments with interleukin-2 and vaccines that stimulate the body to attack the melanoma cells have yielded promising results.

Because melanoma is often caused by long-term sun exposure, people can help prevent this cancer by staying out of the sun and using protective clothing and sunscreen, starting in early childhood. Anyone who has had a melanoma is at risk of developing other melanomas. Therefore, such people need yearly skin examinations. People with a lot of moles should have total body skin examinations at least once a year.

Adapted from: Merck & Co. Inc.