Q: What is nonmelanoma skin cancer?
Although there are several types of non-melanoma skin cancer (NMSC), the most common types are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These skin cancers account for 90% of all cases of skin cancer. Other NMSC’s include cutaneous lymphomas, merkel cell carcinoma, and Kaposi sarcoma. Approximately 20% of all Americans, an estimated 67,720 people in 2008, will develop NMSC during their lifetime.
Basal cell carcinomas develop from cells in the deepest layer (basal layer) of the superficial skin (epidermis) called basal cells. These cells help to replenish the skin by continually dividing to produce cells called keratinocytes. The keratinocytes are the cells that make up the majority of the epidermis. Squamous cell carcinomas develop from keratinocytes.
Several other skin lesions may be confused with NMSC or may develop into NMSC including seborrheic keratoses, actinic keratoses (which are precancerous lesions), cutaneous horns, and sebaceous gland hyperplasia. Therefore, any skin lesions which are new or changing should be evaluated by a physician.
Q: How are the two types of nonmelanoma skin cancer different?
Basal cell skin cancer is the more common of the two types of nonmelanoma skin cancer, accounting for more than 90 percent of all skin cancers in the United States. It usually occurs on areas of the skin that have been in the sun.
Often this cancer appears as a small, fleshy bump or nodule on the head, neck, or hands. Sometimes the nodules are flat growths that appear on the trunk of the body.
Basal cell carcinoma is fairly easy to detect, grows very slowly (it may take months or years for a tumor to reach a diameter of a half-inch), and has an excellent record for successful treatment. The relative five-year survival rate is more than 99 percent when properly treated.
Basal cell cancers usually do not spread to other parts of the body but they sometimes spread to tissues around the cancer. They can extend below the skin to the bone and can cause considerable local damage as a result. In addition, nonmelanoma skin cancer puts people at a greater risk for developing additional cancers.
Squamous cell tumors also occur on areas of the skin that have been in the sun, often on the top of the nose, forehead, lower lip, and hands. They may also appear on areas of the skin that have been burned, exposed to chemicals, or had x-ray therapy.
Often this cancer appears as a firm red bump or scaly red patch. In a few percent of cases squamous cell tumors spread to other parts of the body, develop into masses, and metastasize. The overall five-year survival rate for patients with squamous cell carcinoma of the skin is more than 95 percent.
Q: What are the causes and risk factors?
The most important contributor to the incidence of skin cancer -- the most common type of cancer throughout the world -- is the powerful effect of the sun's ultraviolet (UV) light.
Overexposure to the sun permanently damages the skin and can lead to skin cancer. Due to a reduction of ozone in the earth's atmosphere, the level of UV light today is higher than it was 50 or 100 years ago and the incidence of skin cancer is on the rise.
Ozone serves as a filter to screen out and reduce the amount of UV light that we are exposed to. With less atmospheric ozone, a higher level of UV light reaches the earth's surface.
The amount of exposure and intensity of exposure one has to the sun's UV rays are influenced by both lifestyle and geographic factors. People who spend a lot of time in the sun increase their risk of developing skin cancer.
In addition, people who live or spend time at high altitudes (where the thinner air cannot filter UV as effectively as it does at sea level) or at latitudes close to the equator (where the earth is closer to the sun) may have a higher risk of developing skin cancer.
On the other hand, people who live in areas that have regular or frequent cloud cover may actually be exposed to as much as 50 percent less UV light.
Two other factors may be influential in determining a person's risk for developing skin cancer:
Heredity: People with a family history of skin cancer are generally at a higher risk of developing the disease. People with fair skin and a northern European heritage appear to be most susceptible.
Multiple or atypical nevi (moles): People whose skin has lots of moles or atypical moles may have a slightly greater chance of developing cancer.
Q: What are the treatment options available?
There are three primary treatments for patients with skin cancer: surgery, chemotherapy, and radiation therapy.
In addition, biological therapy and photodynamic therapy are being studied. The choice of treatment depends on the location and extent of the cancer and the patient's overall health.
Surgery is the most common treatment for skin cancer and is used in the treatment of about 90 percent of skin cancer cases.
A doctor may remove the cancer using one of the following procedures:
Electrodesiccation and curettage uses an electric current to dehydrate the tumor (electrodesiccation), then often uses a specialized surgical tool (curet) to remove the tumor.
Cryosurgery involves freezing the tumor.
Simple excision cuts the cancer from the skin along with some of the healthy tissue around it.
Micrographic surgery is removal of the cancer and as little normal tissue as possible. During this surgery, the doctor removes the cancer and then uses a microscope to look at the cancerous area to make sure no cancer cells remain.
Laser therapy uses a highly focused beam of light that destroys only the cancer cells.
Surgery may leave a scar on the skin. Depending on the size of the cancer, skin may be taken from another part of the body and put on the area where the cancer was removed. This is called a skin graft.
Radiation therapy uses x-rays to kill cancer cells and shrink tumors. Radiation therapy for skin cancer comes from a machine outside the body (external radiation therapy).
Chemotherapy uses drugs to kill cancer cells. In treating skin cancer, chemotherapy is often given as a cream or lotion placed on the skin to kill cancer cells (topical chemotherapy).
Chemotherapy may also be taken by pill, or it may be injected into a vein or muscle with a needle. Chemotherapy given in this way is called a systemic treatment because the drug enters the bloodstream, travels through the body, and can kill cancer cells outside the skin. Systemic chemotherapy for skin cancer is being tested in clinical trials.
Biological therapy (using the body's immune system to fight cancer) is also being tested in clinical trials.
Biological therapy tries to get the body to fight cancer. It uses materials made by the body or made in a laboratory to boost, direct, or restore the body's natural defenses against disease. Biological therapy is sometimes called biological response modifier (BRM) therapy or immunotherapy.
Photodynamic therapy uses a certain type of light and a special chemical to kill cancer cells.
Q: Are there any clinical trials for nonmelanoma skin cancer?
Another treatment option available to some patients is to participate in a study of a new cancer treatment.
Every successful cancer treatment being used today was first tested in a clinical trial, a three-step research process designed to evaluate the safety and effectiveness of new treatments for diseases.
Clinical trials are conducted at the end of a much longer process of developing and testing new therapies in the laboratory. Patients who participate in successful trials are the first to benefit from the new therapy.
Doctors in many hospitals and cancer centers across the country conduct clinical trials as new drugs and other therapies become available for treating cancer patients. Each carefully planned study is designed to answer certain questions and to find out specific information about how well a new drug or treatment method works.
All new treatments must go through three steps or phases of clinical trials:
Phase I trials: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the muscle), how often, and in what dose. A Phase I trial usually involves only a small number of patients, sometimes as few as a dozen.
Phase II trials: A Phase II trial continues to test the safety of the drug and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular type of cancer.
Phase III trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard for treatment. A participant will usually be assigned to the standard treatment group or the new treatment group at random (called randomization). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide.
All clinical trial participants receive the best care possible, and their reactions to the treatment are watched very closely. If the treatment does not seem to be helping, a doctor can take a patient out of a study. A patient may choose to leave a trial at any time. If a patient leaves a research study for any reason, standard care and treatment are still available.
Clinical Trials at The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center.