Skin cancer is the most common of all cancers in the United States, accounting for as much as half of all cancer diagnoses, according to the American Cancer Society (ACS). It is also among the most curable, especially when caught in its early stages.

Skin cancer is divided into two main categories – melanoma and non-melanoma. Non-melanoma skin cancers are far more common, and less dangerous, than melanoma skin cancer. Melanoma skin cancers account for 4 percent of skin cancers overall, but cause 75 percent of skin cancer-related deaths each year, according to the Occupational Safety and Health Administration (OSHA).

The two most common forms of non-melanoma skin cancer are basal cell carcinoma, which begins in the skin’s lowest layer, and squamous cell carcinoma, which occurs in the higher layers of the skin. Squamous cell carcinoma rarely spreads (metastasizes) to other parts of the body. Basal cell carcinoma is unlikely to spread, but can invade other sites if left untreated.

Most cases of non-melanoma skin cancers are caused by overexposure to the sun’s ultraviolet (UV) rays. People with lightly pigmented skin, and those who have previously developed skin cancer, have the greatest risk of developing non-melanoma skin cancer. The ACS notes that more than 1 million cases of non-melanoma skin cancers are diagnosed every year and the incidence is rising. Many of these cases can be prevented by simply avoiding prolonged exposure to the sun, especially during peak hours and protecting skin with opaque clothing and sunscreen.

The most important warning sign of skin cancer is a new growth or spot on the skin that changes in size, shape, texture or color. A physical examination, followed by a skin biopsy taken from the suspected area will be used to diagnose whether cancer is present and, if present, its type and stage.

When skin cancer is detected early, it is highly treatable, usually with a simple excision (surgical removal). If not detected early, more aggressive surgery may be required.  In the early stages, non-melanoma skin cancer has an excellent prognosis.

Non-melanoma skin cancer is the most common form of cancer to occur in the United States. More than 1 million cases of non-melanoma skin cancer are diagnosed each year, according to the American Cancer Society (ACS). It is difficult to determine the exact number of individuals who develop the condition as many cases are not reported. About half of all Americans who live to age 65 will be diagnosed with skin cancer.

Very few people die from non-melanoma skin cancer. The ACS estimates that about 2,700 people in the United States will die from this type of cancer in 2007. Most of these individuals are elderly and did not receive treatment in the early stages of the disease. People with compromised immune systems also have a higher risk of mortality.

Another form of skin cancer, melanoma, is responsible for more than 75 percent of skin cancer-related deaths. It is important to note, however, that this type of skin cancer accounts for less than 4 percent of skin cancer diagnoses, according to the ACS. 

The two most common forms of non-melanoma skin cancer are basal cell carcinoma and squamous cell carcinoma. To understand how these forms differ, it is helpful to know a little about the skin's anatomy.

The skin is made up of three layers – the epidermis, the dermis and the subcutaneous (also called the subcutis) layer. Non-melanoma skin cancers originate in the epidermal layer. The epidermis itself is divided into several sub-layers, including the stratum corneum. Dead cells are pushed to the top of the stratum corneum, which forms the top of the epidermis. As they move upward, these cells (keratinocytes) flatten out. Eventually, they are shed and replaced.

These cells are considered squamous cells, because of their fish scale-like shape. Just below this sublayer of dead cells are live keratinocytes, which produce a substance called keratin. Keratin is a sturdy protein that forms the upper layers of the skin, nails and hair.

The innermost layer of the epidermis is the basal layer, made up of basal cells. As these basal cells divide, they form new keratinocytes as older ones are shed from the skin’s surface. A basement membrane further separates the dermis and the subcutaneous layer from the epidermis.

Like all cancers, non-melanoma skin cancer occurs when DNA, the genetic blueprint that controls how cells grow and behave, becomes damaged and is not repaired. This damage causes the cells to multiply continuously until they form a growth or tumor (a mass of excess tissue).

More than 75 percent of all non-melanoma skin cancers diagnosed in the United States are basal cell carcinomas, according to the ACS. Basal cell carcinoma develops and grows slowly over time, and rarely spreads (metastasizes) to other parts of the body. It tends to develop on the sun-exposed areas of the body (e.g., face, ears neck, scalp, shoulders, back).  

Squamous cell carcinoma, the second most common skin cancer, is also slow-growing, but can penetrate deeper layers of the skin if left untreated. In rare cases, it can be fatal if it metastasizes to other organs. Squamous cell carcinoma can develop on all areas, but it most commonly occurs on sun-exposed areas of the body. The rim of the ears and lower lip are especially vulnerable.

Squamous cell carcinoma can occur without warning on apparently healthy, undamaged skin. Scientists are unsure why the condition develops but hereditary may play a role.

Basal cell carcinoma and squamous carcinoma are the two main forms of non-melanoma skin cancer. Together, they account for about 95 percent of all non-melanoma skin cancers, according to the American Cancer Society.

Other forms are much rarer and they include Kaposi’s sarcoma, which begins in the blood vessels of the skin and produces red or purple patches in the skin or mucous membranes. As with melanoma, Kaposi’s sarcoma can be a deadly form of skin cancer. It is most often seen in those individuals who already have a compromised immune system, such as those infected with HIV or those who have full-blown AIDS. It also occurs with individuals who have undergone an organ transplant and are taking immunosuppressive medications.

Cutaneous lymphoma, skin adnexal tumors, Merkel cell carcinoma and various types of sarcomas are other less common forms of non-melanoma skin cancer. Additionally, actinic keratoses, also known as solar keratoses, can develop into non-melanoma skin cancer in a small number of affected people.

This skin condition is characterized by rough, scaly patches that range in color from brown to dark pink. These patches are often found on fair-skinned people who have skin damage from overexposure to the sun’s ultraviolet (UV) rays, especially on the face, ears, lower arms and hands.

A risk factor is anything that increases a person’s chance of developing a specific disease. The most common cause for all skin cancers (non-melanoma and melanoma) is excessive exposure to the sun.

People whose occupations or lifestyle habits keep them exposed to the sun (or indoor tanning lamps) are at the greatest risk. People with fair skin, light eyes or light hair color are also at higher risk for developing non-melanoma skin cancer. Those who have darker skin tones are at lower risk for skin cancer, but if it occurs it is more likely to metastasize.

Other general risk factors include the following:

• Gender. Men are more likely to develop skin cancer than women, but this may be attributed to increased sun exposure.
  
  
• Chemical exposure. Contact with carcinogens (cancer-causing substances), such as arsenic, industrial tar, coal, paraffin, some petroleum byproducts, creosote (a wood preservative) and radium increases the risk of non-melanoma skin cancer.
  
  
• Skin inflammation or injury. Burns, scars, and skin conditions such as eczema can increase risk. Tattoos also make the skin more vulnerable.
  
  
• Family history of skin cancer. A family history of nonmelanoma skin cancer increases an individual’s risk of developing it.
  
  
• Personal history of skin cancer. Once a person has had a non-melanoma skin cancer, the risk of developing another is increased.
  
  
• Reduced immunity. This includes individuals infected with HIV, those who have full-blown AIDS or those taking immunosuppressive therapy (medications that may suppress the immune system).
  
  
• Living in a sunny or high-altitude climate. Those who live along the Sunbelt and those who live at high altitudes that have less than normal amounts of atmosphere for protection have an increased risk of developing skin cancer.
  
  
• Tobacco use. Any type of tobacco use, particularly smoking cigarettes, increases a person’s risk of many types of cancer, including most forms of skin cancer.
  
  
• Actinic keratosis. This skin condition may lead to squamous cell carcinoma in a small number of individuals. It is also related to sun exposure.
  
  
• Some psoriasis treatments are said to increase the risk of developing non-melanoma skin cancer.

In addition to general risk factors for non-melanoma skin cancer, there are also genetic syndromes that may predispose a person to developing this common form of cancer. These include:

• Xeroderma pigmentosum. A rare, inherited condition that impairs the body’s ability to repair DNA damage caused by sunlight.
  
  
• Albinism. A rare, inherited condition in which a person is born without pigment in the skin or hair.
  
  
• Nevoid basal cell carcinoma syndrome. A rare genetic disorder characterized by a predisposition to cancer, especially basal cell carcinoma before the age of 20, and other birth defects.
  
  
• Epidermodysplasia verruciformis. A genetic disease characterized by distinctive changes in the skin on the chest and arms and numerous warts on the hands and feet.

Unlike many other forms of cancer, skin cancer has recognizable signs and symptoms. The most important warning sign is a new growth or spot on the skin that changes in size, shape, texture or color. A small lesion or sore that bleeds, scabs or crusts over and reopens may be a warning sign of skin cancer.

Most signs of change in the skin appear on the areas exposed to sun, including the scalp, face, lips, ears (especially the upper rims), neck, chest, back and extremities. However, skin cancer can appear anywhere on the skin – even in areas that are not exposed to the sun, such as the palms of the hands, in between the toes and even in the genital area.

Skin changes may occur over a period of several weeks to one to two years. Such changes should be evaluated immediately by a dermatologist (a doctor who specializes in the physiology or pathology of the skin) or other qualified physician.

Common signs of basal cell carcinoma include:

• A wax-like or pearl-colored bump, often on the face, ears or neck
  
  
• A flat, skin-colored or brown lesion,  often on the chest or back

Common symptoms of squamous cell carcinoma include:

• A reddish nodule with a firm texture, frequently on the face, lips, ears, neck, hands or arms
  
  
• A flat lesion with a crusty or scaly surface that may appear on the face, ears, neck, hands or arms

It is important to note that not all skin changes are cancerous but patients should immediately notify their physician if suspicious growths or changes occur.

Individuals should seek medical advice if a mole or area of the skin begins to change. A medical examination and diagnostic testing can determine if a suspicious area is a melanoma or non-melanoma skin cancer, or some other skin condition.

The most common way for physicians to diagnose skin cancer is to biopsy the suspicious lesion. The removed specimen is sent to an experienced pathologist who views it under a microscope for evidence of cancer. The method of excision (removal) depends on the structure of the lesion. The physician will typically administer a local anesthetic to numb the affected area before performing the biopsy. The three main types of biopsy include:

• Shave. This type of biopsy is normally used for raised lesions, such as nodular basal cell carcinoma or squamous cell carcinoma. After a local anesthetic is applied to the area, the physician uses a surgical blade to shave off the top layers of the suspicious lesion.
  
  
• Punch. This type of biopsy is normally used for removing a flat, broad lesion. A punch biopsy removes a deep sample of skin. During this procedure, the physician rotates a tiny round tool that resembles a cookie cutter until it cuts through all the layers of the skin to extricate the questionable lesion or mole.
  
  
• Incisional or excisional biopsy. For a tumor that has grown into the deeper layers of the skin, a physician will often perform an incisional or excisional biopsy. An incisional biopsy removes a portion of the tumor to be examined later whereas an excisional biopsy removes the entire tumor. These biopsies can help determine whether the tumor is benign or malignant. Excisional biopsy is the recommended method for melanomas.

The goal of treating non-melanoma skin cancer is to destroy or remove the cancer completely with minimal scarring of the patient’s skin. The treatment options for non-melanoma skin cancer depend on a number of factors, including the location of the lesion on the patient’s body. For most squamous cell and basal cell carcinomas, which rarely spread, a biopsy may be the only necessary treatment. However, if additional treatment is required, some common options include:

• Cryosurgery. For certain small skin cancers that are detected in their early stages, cryosurgery (freezing the affected area with liquid nitrogen) may be an appropriate treatment. After the treated area thaws, the dead skin will fall off. This treatment may also be recommended for the treatment of actinic keratoses.
  
  
• Excisional surgery. This is a common form of treatment for any type of skin cancer. During this procedure, the physician surgically removes the suspicious lesion, as well as a surrounding margin of healthy tissue. It is not uncommon for a plastic surgeon to perform excisional surgery of facial lesions.
  
  
• Mohs’ surgery. This form of treatment is often recommended for large skin cancers that are difficult to treat or recurrent skin cancers. This treatment is used for both basal cell carcinoma and squamous cell carcinoma. During this treatment, the lesion is removed one layer at a time and examined under a microscope. The process is repeated until only healthy tissue remains.
  
  
• Curettage and electrodesiccation. This treatment is commonly used for thin or small basal cell carcinomas. During this treatment, the majority of the lesion is removed, and any remaining layers of cancer cells are scraped away using a curet (circular blade). Afterward, an electric needle is used to destroy any remaining cancer cells.
  
  
• Laser therapy. This form of treatment aims a narrow beam of light that vaporizes growths. It is often used for skin cancer lesions that develop on the lips or the outer layer of skin. The advantages of laser therapy include minimal bleeding, swelling or scarring.
  
  
• Skin grafting and reconstructive surgery. Skin cancers that are particularly large may require a deep and/or wide excision. Afterward, there may not be enough skin left to close the wound. For these cases, skin grafts (taking skin from another area, such as the buttocks or thighs) can fill in some of the removed tissue and restore a more normal appearance to the area.

In some cases, the cancer may be in a sensitive or hard-to-reach area, such as the eyelid, tip of the nose or the ear. These locations can make surgery difficult and radiation therapy may be used for treatment. For skin cancer limited to the top of the skin, chemotherapy can be effective. This type of chemotherapy is usually applied as a cream or lotion.

Other therapeutic approaches to treatment are still under investigation. Two of the most promising treatments for skin cancer that are being studied include:

• Photodynamic therapy. Using a laser light and medications that sensitize cancer cells to light, this form of treatment helps destroy skin cancer cells. Currently, it is used for precancerous skin lesions.
  
  
• Retinoid therapy. Retinoids are substances that help regulate the work of genes as cells grow and divide. Chemically related to vitamin A, retinoids are used to treat a wide variety of conditions and diseases, including several cancers. Retinoids have been approved by the U.S. Food and Drug Administration (FDA) for use in the treatment of certain cancers, particularly skin cancers. They are usually administered in a topical gel or orally, depending on the condition being treated.

All individuals should be aware that exposure to the sun and its ultraviolet (UV) rays can cause skin cancer. The sun emits two types of ultraviolet radiation – ultraviolet A (UVA) and ultraviolet B (UVB), both of which can damage the skin. UVA damage can reach the deepest layers of the skin, possibly resulting in damage to the skin’s immune defenses and even cancer. UVB rays lead to sunburn and are often implicated in the development of less deadly forms of skin cancer, including basal cell carcinomas and squamous cell carcinomas. The Occupation Safety and Health Administration (OSHA) recommends the following steps to prevent non-melanoma and other skin cancers:

• Cover up. Tightly woven clothing is more effective at blocking out sun and keeping it from damaging the skin. Several companies make sun-resistant clothing.
  
  
• Use sunscreen. Frequently apply sunscreen with a sun protection factor (SPF) of at least 15, which will block 93 percent of UV rays. It is important to follow the directions on the bottle, including when to reapply. Note: SPF ratings refer only to UVB protection. Be sure to choose a product that includes protection against both UVA and UVB rays (e.g., products containing zinc oxide or titanium dioxide). Sunscreen should be applied 30 minutes before going outside and reapplied after swimming or sweating.
  
  
• Wear a hat. A baseball cap or visor offers little or no protection for the ears and neck. A wide-brimmed hat is a far better choice since it will protect the ears, neck, eyes, forehead, nose and scalp.
  
  
• Wear UV-absorbent sunglasses. Even inexpensive sunglasses can be effective. Look for ones that block 99 to 100 percent of UVA and UVB radiation. Wrap-around glasses offer the best protection as they shade the sides of the eyes as well.
  
  
• Limit sun exposure. The rays of the sun are the strongest, and thus cause the most damage, between 10 a.m. and 4 p.m. If it is not possible to avoid those hours, seek shade under a tree, beach umbrella or tent.
  
  
• Avoid tanning beds. In addition to the possibility of infections and warts, tanning beds are not a safe way to get a tan because they also emit UV rays just like the sun.
  
  
• Check medications. Some prescription drugs increase a person’s sensitivity to sunlight, increasing the risk of sunburn. Common medications that increase sensitivity include thiazides, diuretics, tetracycline, sulfa antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.
  
  
• Regular examinations by a physician.  Routine examinations by a physician qualified to diagnose skin cancer are important to those with a low or normal risk, and even more important to those with an increased risk of developing non-melanoma skin cancer. From ages 20 to 39, a full-body screening by a dermatologist (a doctor that specializes in the physiology or pathology of the skin) is recommended every three years. After the age of 40, patients should be examined annually. For individuals who previously have had skin cancer, it is best to follow the treating physician’s recommendations for follow-up care. In between clinical exams, monthly self-examinations are recommended.
  

The damaging effects of the sun can be more dramatic at higher elevations where there is little atmosphere to filter the sunlight. Snow, as well as sand or water, can reflect the UV rays of the sun and can lead to sunburn and permanent damage to the skin, just as direct sunlight can.

The prognosis (predicted outlook or chance of survival) of non-melanoma skin cancer depends on the cancer’s stage and grade. The stage indicates the extent of the cancer, or how widespread it is in the body. The grade measures how abnormal the cells look under a microscope. The grading and staging systems are combined into another system that allows the physician to discuss the pathology of the tumor in layman’s terms. These stages include:

• Stage 0. This is the earliest stage of skin cancer. The lesion is still at the epidermis level and has not spread to the dermis.
  
  
• Stage I. The cancer is less than or equal to 2 centimeters (about 7/8 of an inch). It may have spread to the dermis, but not to nearby lymph nodes or other organs.
  
  
• Stage II. The cancer is larger than 2 centimeters, but has not spread to nearby lymph nodes or other organs.
  
  
• Stage III. The cancer has spread to lymph nodes and/or subcutaneous tissue (e.g., muscle, bone or cartilage) but has not invaded other organs, such as the brain or lungs.
  
  
• Stage IV: The cancer is any size and has spread to distant sites or organs, such as the brain or lungs. The cancer may or may not have invaded nearby lymph nodes.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor or other healthcare professional the following questions about non-melanoma skin cancer:

1. Am I at higher risk for non-melanoma skin cancer?
   
   
2. How will I know if a lesion is suspicious?
   
   
3. How often should I be screened for skin cancer?
   
   
4. Can you recommend good sunscreens and skin products?
   
   
5. Can non-melanoma skin cancer become melanoma skin cancer?
   
   
6. What type of non-melanoma cancer do I have?
   
   
7. What is the stage of the cancer and my prognosis?
   
   
8. What are my treatment options?
   
   
9. What are the risks with these treatments?
   
   
10. What will be involved in the recovery from treatment?
    
    
11. Will I have a scar from the biopsy or treatment?
    
    
12. What are the chances that the skin cancer will return?
    
    
13. How will you know if you have removed all of the cancer?
    
    
14. If I develop non-melanoma skin cancer, does it mean I have to avoid all sun exposure in the future?
    
    
15. Are my children at higher risk for this cancer if I develop it?