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 (the first stage of which is called actinic keratosis)
* 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. Skin cancer is also known as skin neoplasia.
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% 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, sun exposure, and age are all important factors in the development of basal cell carcinomas. People who have fair skin and are older have higher rates of basal cell carcinoma. About 20% 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. Other risk factors include
* exposure to sun
* age. 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.
* exposure to ultraviolet radiation in tanning booths. Tanning booths are very popular, especially among adolescents, and they even let people who live in cold climates radiate their skin year-round.
* therapeutic radiation, such as that given for treating other forms of cancer.
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.
Superficial basal cell carcinomas often appear on the chest or back and look more like patches of raw, dry skin. They grow slowly over the course of months or years.
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.
* 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.
* Medical therapy using creams that attack cancer cells (5-Fluorouracil--5-FU, Efudex, Fluoroplex) or stimulate the immune system (imiquimod [Aldara]).
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 30 or higher;
* undergoing regular checkups and bringing any suspicious-looking or changing lesions to the attention of the doctor; and
* avoiding the use of tanning beds and using a sunscreen with an SPF of 30 and protection against UVA (long waves of ultraviolet light).
Squamous Cell Carcinoma
What is squamous cell carcinoma?
Squamous cell carcinoma is cancer that begins in the squamous cells, which are thin, flat cells that look like fish scales under the microscope. The word squamous came from the Latin squama, meaning "the scale of a fish or serpent" because of the appearance of the cells.
Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Thus, squamous cell carcinomas can actually arise in any of these tissues.
Squamous cell carcinoma of the skin occurs roughly one-quarter as often as basal cell carcinoma. Light-colored skin and a history of sun exposure are even more important in predisposing to this kind of cancer than to basal cell carcinoma. Men are affected more often than women. Patterns of dress and hairstyle may play a role. Women, whose hair generally covers their ears, develop squamous cell carcinomas far less often in this location than do men.
The earliest form of squamous cell carcinoma is called actinic (or solar) keratosis. Actinic keratoses appear as rough, red bumps on the scalp, face, ears, and backs of the hands. They often appear against a background of mottled, sun-damaged skin. They can be quite sore and tender, out of proportion to their appearance.
A rapidly-growing form of squamous cell carcinoma that forms a mound with a central crater is called a keratoacanthoma. While some consider this not a true cancer but instead a condition that takes care of itself, most pathologists consider it to be a form of squamous cell cancer and clinicians treat is accordingly.
Other forms of squamous cell carcinoma that have not yet invaded deeper into the skin include
* actinic cheilitis, involving the lower lip with redness and scale, and blurring the border between the lip and the surrounding skin;
* Bowen's disease, sometimes referred to as squamous cell carcinoma in situ. (The Latin words in situ refer to the presence of the cancer only in the superficial epidermis, without deeper involvement.)
* Bowenoid papulosis: These are genital warts that under the microscope look like Bowen's disease but behave like warts, not like cancers.
What are risk factors for developing squamous cell carcinoma?
The single most important factor in producing squamous cell carcinomas is sun exposure. Many such growths can develop from precancerous spots, called actinic or solar keratoses. These lesions appear after years of sun damage on parts of the body like the forehead and cheeks, as well as the backs of the hands. Sun damage takes many years to promote skin cancer. It is therefore common for people who stopped being "sun worshipers" in their 20s to develop precancerous or cancerous spots decades later.
Several rather uncommon factors may predispose to squamous cell carcinoma. These include exposure to arsenic, hydrocarbons, heat, or X-rays. Some squamous cell carcinomas arise in scar tissue. Suppression of the immune system by infection or drugs may also promote such growths. Some strains of HPV (the human papillomavirus responsible for causing genital warts) can promote development of squamous cell carcinoma in the anogenital region.
Can squamous cell carcinoma of the skin spread (metastasize)?
Yes. Unlike basal cell carcinomas, squamous cell carcinomas can metastasize, or spread to other parts of the body. These tumors usually begin as firm, skin-colored or red nodules. Squamous cell cancers that start out within solar keratoses or on sun-damaged skin are easier to cure and metastasize less often than those that develop in traumatic or radiation scars. One location particularly prone to metastatic spread is the lower lip. A proper diagnosis in this location is, therefore, especially important.
How is squamous cell carcinoma diagnosed?
As with basal cell carcinoma, doctors usually perform a biopsy to make a proper diagnosis. This involves taking a sample by injecting local anesthesia and punching out a small piece of skin using a circular punch blade. Usually the method used referred to as a punch biopsy. The skin that is removed is then examined under a microscope to check for cancer cells.
How is squamous cell carcinoma treated?
Techniques for treating squamous cell carcinoma are similar to those for basal cell carcinoma (for detailed descriptions, see above under treatment of basal cell carcinoma):
* Curettage and desiccation
* Surgical excision
* Radiation therapy:
* Cryosurgery
* Mohs micrographic surgery
* Medical therapy
How is squamous cell carcinoma prevented?
Even more so than is the case with basal cell carcinoma, the key principles of prevention are minimizing sun exposure and getting regular checkups.
Common-sense preventive techniques are the same as for basal cell carcinoma and 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 30 or higher;
* undergoing regular checkups and bringing any suspicious-looking or changing lesions to the attention of a doctor; and
* avoiding the use of tanning beds and using a sunscreen with an SPF 30 and protection against UVA (long waves of ultraviolet light).
