Skin Cancer

Skin cancer is the most common form of human cancer. It is estimated that over 1 million new cases occur annually. The annual rates of all forms of skin cancer are increasing each year, representing a growing public concern. It has also been estimated that nearly half of all Americans who live to age 65 will develop skin cancer at least once.

The most common warning sign of skin cancer is a change in the appearance of the skin, such as a new growth or a sore that will not heal.

The term "skin cancer" refers to three different conditions. From the least to the most dangerous, they are:

• basal cell carcinoma (or basal cell carcinoma epithelioma)
• squamous cell carcinoma
• melanoma

The two most common forms of skin cancer are basal cell carcinoma and squamous cell carcinoma. Together, these two are also referred to as nonmelanoma skin cancer. Melanoma is generally the most serious form of skin cancer because it tends to spread (metastasize) throughout the body quickly.

This article will discuss the two kinds of nonmelanoma skin cancer. For information about melanoma, please read the Melanoma article.

Basal Cell Carcinoma

What is basal cell carcinoma?

Basal cell carcinoma is the most common form of skin cancer and accounts for more than 90 percent of all skin cancer in the U.S. These cancers almost never spread (metastasize) to other parts of the body. They can, however, cause damage by growing and invading surrounding tissue.

What are risk factors for developing basal cell carcinoma?

Light-colored skin and sun exposure are both important factors in the development of basal cell carcinomas. About 20 percent of these skin cancers, however, occur in areas that are not sun-exposed, such as the chest, back, arms, legs, and scalp. The face, however, remains the most common location for basal cell lesions. Weakening of the immune system, whether by disease or medication, can also promote the risk of developing basal cell carcinoma.

According to the U.S. National Institutes of Health, ultraviolet (UV) radiation from the sun is the main cause of skin cancer. Artificial sources of UV radiation, such as sunlamps and tanning booths, can also cause skin cancer. The risk of developing skin cancer is also affected by where a person lives. People who live in areas that receive high levels of UV radiation from the sun are more likely to develop skin cancer. In the United States, for example, skin cancer is more common in Texas than it is in Minnesota, where the sun is not as strong. Worldwide, the highest rates of skin cancer are found in South Africa and Australia, which are areas that receive high amounts of UV radiation. In addition, skin cancer is related to lifetime exposure to UV radiation. Most skin cancers appear after age 50, but the sun's damaging effects begin at an early age. Therefore, protection should start in childhood in order to prevent skin cancer later in life.

What does basal cell carcinoma look like?

A basal cell carcinoma usually begins as a small, dome-shaped bump and is often covered by small, superficial blood vessels called telangiectases. The texture of such a spot is often shiny and translucent, sometimes referred to as "pearly." It is often hard to tell a basal cell carcinoma from a benign growth like a flesh-colored mole without performing a biopsy. Some basal cell carcinomas contain melanin pigment, making them look dark rather than shiny.

Basal cell carcinomas grow slowly, taking months or even years to become sizable. Although spread to other parts of the body (metastasis) is very rare, a basal cell carcinoma can damage and disfigure the eye, ear, or nose if it grows nearby.

How is basal cell carcinoma diagnosed?

To make a proper diagnosis, doctors usually remove all or part of the growth by performing a biopsy. This usually involves taking a sample by injecting a local anesthesia and scraping a small piece of skin. This method is referred to as a shave biopsy. The skin that is removed is then examined under a microscope to check for cancer cells.

How is basal cell carcinoma treated?

There are many ways to successfully treat a basal cell carcinoma with a good chance of success of 90% or more. The doctor's main goal is to remove or destroy the cancer completely with as small a scar as possible. To plan the best treatment for each patient, the doctor considers the location and size of the cancer, the risk of scarring, and the person's age, general health, and medical history.

Methods used to treat basal cell carcinomas include:

• Curettage and desiccation: Dermatologists often prefer this method, which consists of scooping out the basal cell carcinoma by using a spoon like instrument called a curette. Desiccation is the additional application of an electric current to control bleeding and kill the remaining cancer cells. The skin heals without stitching. This technique is best suited for small cancers in non-crucial areas such as the trunk and extremities.
  
  
• Surgical excision: The tumor is cut out and stitched up.
  
  
• Radiation therapy. Doctors often use radiation treatments for skin cancer occurring in areas that are difficult to treat with surgery. Obtaining a good cosmetic result generally involves many treatment sessions, perhaps 25 to 30.
  
  
• Cryosurgery: Some doctors trained in this technique achieve good results by freezing basal cell carcinomas. Typically, liquid nitrogen is applied to the growth to freeze and kill the abnormal cells.
  
  
• Mohs micrographic surgery: Named for its pioneer, Dr. Frederic Mohs, this technique of removing skin cancer is better termed, "microscopically controlled excision." The surgeon meticulously removes a small piece of the tumor and examines it under the microscope during surgery. This sequence of cutting and microscopic examination is repeated in a painstaking fashion so that the basal cell carcinoma can be mapped and taken out without having to estimate or guess the width and depth of the lesion. This method removes as little of the healthy normal tissue as possible. Cure rate is very high, exceeding 98%. Mohs micrographic surgery is preferred for large basal cell carcinomas, those that recur after previous treatment, or lesions affecting parts of the body where experience shows that recurrence is common after treatment by other methods. Such body parts include the scalp, forehead, ears, and the corners of the nose. In cases where large amounts of tissue need to be removed, the Mohs surgeon sometimes works with a plastic (reconstructive) surgeon to achieve the best possible post-surgical appearance.

How is basal cell carcinoma prevented?

Avoiding sun exposure in susceptible individuals is the best way to lower the risk for all types of skin cancer. Regular surveillance of susceptible individuals, both by self-examination and regular physical examination, is also a good idea for people at higher risk. People who have already had any form of skin cancer should have regular medical checkups.

• Common sense preventive techniques include:
• Limiting recreational sun exposure
• Avoiding unprotected exposure to the sun during peak radiation times (the hours surrounding noon)
• Wearing broad-brimmed hats and tightly-woven protective clothing while outdoors in the sun
• Regularly using a waterproof or water resistant sunscreen with UVA protection and SPF number of 30 or higher
• Undergoing regular checkups and bringing any suspicious-looking or changing lesions to the attention of the doctor