Skin Cancer

What are basal and squamous cell skin cancers?

To understand basal and squamous cell skin cancers, it helps to know about the normal structure and function of the skin.

Normal skin

The skin is the largest organ in your body. It does many different things:

  • Covers the internal organs and helps protect them from injury
  • Serves as a barrier to germs such as bacteria
  • Prevents the loss of too much water and other fluids
  • Helps control body temperature
  • Protects the rest of the body from ultraviolet (UV) rays
  • Helps the body make vitamin D

The skin has 3 layers: the epidermis, the dermis, and the subcutis (see picture).

 

Epidermis

The top layer of skin is the epidermis. The epidermis is thin, averaging only 0.2 millimeters thick (about 1/100 of an inch). It protects the deeper layers of skin and the organs of the body from the environment.

Keratinocytes are the main cell type of the epidermis. These cells make an important protein called keratin that helps the skin protect the rest of the body.

The outermost part of the epidermis is called the stratum corneum. It is composed of dead keratinocytes that are continually shed as new ones form. The cells in this layer are called squamous cells because of their flat shape.

Living squamous cells are found just below the stratum corneum. These cells have moved here from the lowest part of the epidermis, the basal layer. The cells of the basal layer, called basal cells, continually divide to form new keratinocytes. These replace the older keratinocytes that wear off the skin’s surface.

Cells called melanocytes are also found in the epidermis. These skin cells make a brown pigment called melanin. Melanin gives the skin its tan or brown color. It protects the deeper layers of the skin from some of the harmful effects of the sun. When skin is exposed to the sun, melanocytes make more of the pigment, causing the skin to tan or darken.

The epidermis is separated from the deeper layers of skin by the basement membrane. This is an important structure because when a skin cancer becomes more advanced, it generally grows through this barrier and into the deeper layers.

Dermis

The middle layer of the skin is called the dermis. The dermis is much thicker than the epidermis. It contains hair follicles, sweat glands, blood vessels, and nerves that are held in place by a protein called collagen. Collagen, made by cells called fibroblasts, gives the skin its elasticity and strength.

Subcutis

The deepest layer of the skin is called the subcutis. The subcutis and the lowest part of the dermis form a network of collagen and fat cells. The subcutis helps the body conserve heat and has a shock-absorbing effect that helps protect the body’s organs from injury.

Types of skin cancer

Melanomas

Cancers that develop from melanocytes, the pigment-making cells of the skin, are called melanomas. Melanocytes can also form benign growths called moles. Melanoma and moles are discussed in our document, Melanoma Skin Cancer.

Skin cancers that are not melanoma are sometimes grouped together as non-melanoma skin cancers because they tend to act very differently from melanomas.

Keratinocyte cancers

These are by far the most common skin cancers. They are called keratinocyte carcinomas or keratinocyte cancers because when seen under a microscope, their cells share some features of keratinocytes, the most common cell type of normal skin. Most keratinocyte cancers are basal cell carcinomas or squamous cell carcinomas.

Basal cell carcinoma

This is not only the most common type of skin cancer, but the most common type of cancer in humans. About 8 out of 10 skin cancers are basal cell carcinomas (also called basal cell cancers). They usually develop on sun-exposed areas, especially the head and neck. Basal cell carcinoma was once found almost entirely in middle-aged or older people. Now it is also being seen in younger people, probably because they are spending more time out in the sun.

When seen under a microscope, basal cell carcinomas share features with the cells in the lowest layer of the epidermis, called the basal cell layer. These cancers tend to grow slowly. It is very rare for a basal cell cancer to spread to nearby lymph nodes or to distant parts of the body. But if a basal cell cancer is left untreated, it can grow into nearby areas and invade the bone or other tissues beneath the skin.

After treatment, basal cell carcinoma can recur (come back) in the same place on the skin. People who have had basal cell cancers are also more likely to get new ones elsewhere on the skin. As many as half of the people who are diagnosed with one basal cell cancer will develop a new skin cancer within 5 years.

Squamous cell carcinoma

About 2 out of 10 skin cancers are squamous cell carcinomas (also called squamous cell cancers). The cells in these cancers share features with the squamous cells seen in the outer layers of the skin.

These cancers commonly appear on sun-exposed areas of the body such as the face, ears, neck, lips, and backs of the hands. They can also develop in scars or chronic skin sores elsewhere. They sometimes start in actinic keratoses (described below). Less often, they form in the skin of the genital area.

Squamous cell carcinomas tend to grow and spread more than basal cell cancers. They are more likely to invade fatty tissues just beneath the skin, and are more likely to spread to lymph nodes and/or distant parts of the body, although this is still uncommon.

Keratoacanthomas are dome-shaped tumors that are found on sun-exposed skin. They may start out growing quickly, but their growth usually slows down. Many keratoacanthomas shrink or even go away on their own over time without any treatment. But some continue to grow, and a few may even spread to other parts of the body. Their growth is often hard to predict, and many skin cancer experts consider them a type of squamous cell skin cancer and treat them as such.

Less common types of skin cancer

Along with melanoma and keratinocyte cancers, there are some other much less common types of skin cancer. These cancers are also non-melanoma skin cancers, but they are quite different from keratinocyte cancers and are treated differently. They include:

  • Merkel cell carcinoma
  • Kaposi sarcoma
  • Cutaneous (skin) lymphoma
  • Skin adnexal tumors
  • Various types of sarcomas

Together, these types account for less than 1% of non-melanoma skin cancers.

Merkel cell carcinoma

This uncommon type of skin cancer develops from neuroendocrine cells (hormone-making cells that resemble nerve cells in some ways) in the skin. They are most often found on the head, neck, and arms but can start anywhere.

These cancers are thought to be caused in part by sun exposure and in part by Merkel cell polyomavirus (MCV). About 8 out of 10 Merkel cell carcinomas are thought to be related to MCV infection. MCV is a common virus. Many people are infected with MCV, but it usually causes no symptoms. In a small portion of people with this infection, changes in the virus’ DNA can lead to this form of cancer.

Unlike basal cell and squamous cell carcinomas, Merkel cell carcinomas often spread to nearby lymph nodes and internal organs. They also tend to come back after treatment. Treatment of Merkel cell carcinoma is described in the section, “Treating Merkel cell carcinoma.”

Kaposi sarcoma

This cancer usually starts within the dermis but can also form in internal organs. It is related to infection with Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). Before the mid-1980s, this cancer was rare and found mostly in elderly people of Mediterranean descent. Kaposi sarcoma has become more common because it is more likely to develop in people with human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS). It is discussed in our document, Kaposi Sarcoma.

Skin lymphomas

Lymphomas are cancers that start in lymphocytes, a type of immune system cell found throughout the body, including in the skin.

Most lymphomas start in lymph nodes (bean-sized collections of immune system cells) or internal organs, but some types of lymphoma begin mostly or entirely in the skin. Primary cutaneous lymphoma is the medical term for lymphomas that start in the skin. The most common type of primary cutaneous lymphoma is cutaneous T-cell lymphoma (most of these are called mycosis fungoides). Cutaneous lymphomas are discussed in our document, Lymphoma of the Skin.

Adnexal tumors

These tumors start in the hair follicles or glands (such as sweat glands) of the skin. Benign (non-cancerous) adnexal tumors are common, but malignant (cancerous) ones, such as sebaceous adenocarcinoma and sweat gland adenocarcinoma, are rare.

Sarcomas

Sarcomas are cancers that develop from connective tissue cells, usually in tissues deep beneath the skin. Much less often they may start in the skin’s dermis and subcutis. Several types of sarcoma can start in the skin, including dermatofibrosarcoma protuberans (DFSP) and angiosarcoma (a blood vessel cancer). Sarcomas are discussed in our document, Sarcoma – Adult Soft Tissue Cancer.

Pre-cancerous and pre-invasive skin conditions

These conditions may develop into skin cancer or may be very early stages in the development of skin cancer.

Actinic keratosis (solar keratosis)

Actinic keratosis, also known as solar keratosis, is a pre-cancerous skin condition caused by too much exposure to the sun. Actinic keratoses are usually small (less than 1/4 inch across), rough or scaly spots that may be pink-red or flesh-colored. Usually they develop on the face, ears, backs of the hands, and arms of middle-aged or older people with fair skin, although they can arise on other sun-exposed areas. People with one actinic keratosis usually develop many more.

Actinic keratoses tend to grow slowly. They usually do not cause any symptoms. They often go away on their own, but they may come back. In some cases actinic keratoses may turn into squamous cell cancers.

Even though most actinic keratoses do not become cancers, they are a warning that your skin has suffered sun damage. Some actinic keratoses and other skin conditions that could become cancers may have to be removed. Your doctor should regularly check any that are not removed for changes that could indicate cancer.

Squamous cell carcinoma in situ (Bowen disease)

Squamous cell carcinoma in situ, also called Bowen disease, is the earliest form of squamous cell skin cancer. “In situ” means that the cells of these cancers are still only in the epidermis and have not invaded the dermis.

Bowen disease appears as reddish patches. Compared with actinic keratoses, Bowen disease patches tend to be larger (sometimes over 1/2 inch across), redder, scalier, and sometimes crusted.

Like invasive squamous cell skin cancers, the major risk factor is too much sun exposure. Bowen disease can also occur in the skin of the anal and genital areas. This is often related to sexually transmitted infection with human papilloma viruses (HPVs), the viruses that can also cause genital warts.

Benign skin tumors

Most tumors of the skin are not cancerous and rarely if ever turn into cancers. There are many kinds of benign skin tumors, including:

  • Most types of moles (see our document, Melanoma Skin Cancer for information on moles)
  • Seborrheic keratoses: tan, brown, or black raised spots with a waxy texture or rough surface
  • Hemangiomas: benign blood vessel growths often called strawberry spots or port wine stains
  • Lipomas: soft tumors made up of fat cells
  • Warts: rough-surfaced growths caused by a virus

 

What are the risk factors for basal and squamous cell skin cancers?

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking and excess sun exposure, can be changed. Others, like a person’s age or family history, can’t be changed.

But risk factors don’t tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may have few or no known risk factors. Even if a person with basal or squamous cell skin cancer has a risk factor, it is often very hard to know how much that risk factor may have contributed to the cancer.

The following are known risk factors for basal cell and squamous cell carcinomas. (These factors don’t necessarily apply to other forms of non-melanoma skin cancer, such as Kaposi sarcoma and cutaneous lymphoma.)

Ultraviolet (UV) light exposure

Ultraviolet (UV) radiation is thought to be the major risk factor for most skin cancers. Sunlight is the main source of UV rays, which can damage the DNA in your skin cells. Tanning beds are another source of UV rays. People who get a lot of exposure to light from these sources are at greater risk for skin cancer.

Ultraviolet radiation is divided into 3 wavelength ranges:

  • UVA rays age cells and can damage cells’ DNA. They are mainly linked to long-term skin damage such as wrinkles, but are also thought to play a role in some skin cancers.
  • UVB rays can directly damage DNA, and are the main cause of sunburns. They are also thought to cause most skin cancers.
  • UVC rays don’t get through our atmosphere and therefore are not present in sunlight. They do not normally cause skin cancer.

While UVA and UVB rays make up only a very small portion of the sun’s rays, they are the main cause of the damaging effects of the sun on the skin. UV rays damage the DNA of skin cells. Skin cancers begin when this damage affects the DNA of genes that control skin cell growth. Both UVA and UVB rays damage skin and cause skin cancer. UVB rays are a more potent cause of at least some skin cancers, but based on what is known today, there are no safe UV rays.

The amount of UV exposure a person gets depends on the strength of the rays, the length of time the skin is exposed, and whether the skin is protected with clothing or sunscreen.

People who live in areas with year-round, bright sunlight have a higher risk. For example, the risk of skin cancer is twice as high in Arizona compared to Minnesota. The highest rate of skin cancer in the world is in Australia. Spending a lot of time outdoors for work or recreation without protective clothing and sunscreen increases your risk.

Many studies also point to exposure at a young age (for example, frequent sunburns during childhood) as an added risk factor.

Having light-colored skin

The risk of skin cancer is much higher for whites than for African Americans or Hispanics. This is due to the protective effect of the skin pigment melanin in people with darker skin. Whites with fair (light-colored) skin that freckles or burns easily are at especially high risk. This is one of the reasons for the high skin cancer rate in Australia, where much of the population descends from fair-skinned immigrants from the British Isles.

Albinism is a congenital (present at birth) lack of protective skin pigment. People with this condition may have pink-white skin and white hair. They have a high risk of getting skin cancer unless they are careful to protect their skin.

Older age

The risk of basal and squamous cell skin cancers rises as people get older. This is probably because of the buildup of sun exposure over time. These cancers are now being seen in younger people as well, probably because they are spending more time in the sun with their skin exposed.

Male gender

Men are about twice as likely as women to have basal cell cancers and about 3 times as likely to have squamous cell cancers of the skin. This is thought to be due mainly to higher levels of sun exposure.

Exposure to certain chemicals

Exposure to large amounts of arsenic increases the risk of developing non-melanoma skin cancer. Arsenic is a heavy metal found naturally in well water in some areas. It is also used in making some pesticides.

Workers exposed to industrial tar, coal, paraffin, and certain types of oil may also have an increased risk for non-melanoma skin cancer.

Radiation exposure

People who have had radiation treatment have a higher risk of developing skin cancer in the area that received the treatment. This is particularly a concern in children who have had radiation treatment for cancer.

Previous skin cancer

Anyone who has had a basal or squamous cell cancer has a much higher chance of developing another one.

Long-term or severe skin inflammation or injury

Scars from severe burns, areas of skin over severe bone infections, and skin damaged by some severe inflammatory skin diseases are more likely to develop skin cancers, although this risk is generally small.

Psoriasis treatment

Psoralens and ultraviolet light treatments (PUVA) given to some patients with psoriasis (a long-lasting inflammatory skin disease) can increase the risk of developing squamous cell skin cancer and probably other skin cancers also.

Xeroderma pigmentosum (XP)

This very rare inherited condition reduces the skin’s ability to repair damage to DNA caused by sun exposure. People with this disorder often develop many skin cancers starting in childhood.

Basal cell nevus syndrome (Gorlin syndrome)

In this rare congenital (present at birth) condition, people develop many basal cell cancers over their lifetime. People with this syndrome may also have abnormalities of the jaw and other bones, eyes, and nervous tissue.

Most of the time this condition is inherited from a parent. In families with this syndrome, those affected often start to develop basal cell cancers as children or teens.

Reduced immunity

The immune system helps the body fight cancers of the skin and other organs. People with weakened immune systems (from certain diseases or medical treatments) are more likely to develop non-melanoma skin cancer, including squamous cell cancer and less common types such as Kaposi sarcoma and Merkel cell carcinoma.

For example, people who get organ transplants are usually given medicines that weaken their immune system to prevent their body from rejecting the new organ. This increases their risk of developing skin cancer. The rate of skin cancer in people who have had transplants can be as high as 70% within 20 years after the transplant. Skin cancers in people with weakened immune systems tend to grow faster and are more likely to be fatal.

Treatment with large doses of corticosteroid drugs can also depress the immune system. This may also increase a person’s risk of skin cancer.

Human papilloma virus (HPV) infection

Human papilloma viruses (HPVs) are a group of more than 100 viruses that can cause papillomas, or warts. The warts that people commonly get on their hands and feet are not related to any form of cancer. But some of the HPV types, especially those that people get in their genital and anal area, seem to be related to skin cancers in these areas.

Smoking

People who smoke are more likely to develop squamous cell skin cancer, especially on the lips. Smoking is not a known risk factor for basal cell cancer.

 

Can basal and squamous cell skin cancers be found early?

Basal cell and squamous cell skin cancers can be found early. As part of a routine cancer-related checkup, your health care professional should check your skin carefully.

You can also play an important role in finding skin cancer early. It’s important to check all over your skin, preferably once a month. Self-exams are best done in a well-lit room in front of a full-length mirror. Use a hand-held mirror for areas that are hard to see. Learn the patterns of moles, blemishes, freckles, and other marks on your skin so that you’ll notice any changes.

All areas should be examined, including your palms and soles, scalp, ears, nails, and your back. (For a more thorough description of a skin self-exam, see our document, Skin Cancer: Prevention and Early Detection and the booklet Why You Should Know About Melanoma.) Friends and family members can also help you with these exams, especially for those hard-to-see areas, such as your scalp and back. Be sure to show your doctor any areas that concern you and ask your doctor to look at areas that may be hard for you to see.

Spots on the skin that are new or changing in size, shape, or color should be seen by a doctor promptly. Any unusual sore, lump, blemish, marking, or change in the way an area of the skin looks or feels may be a sign of skin cancer or a warning that it might occur. The skin might become scaly or crusty or begin oozing or bleeding. It may feel itchy, tender, or painful. Redness and swelling may develop.

Basal cell and squamous cell skin cancers can look like a variety of marks on the skin. The key warning signs are a new growth, a spot or bump that’s getting larger over time, or a sore that doesn’t heal within a couple of months. (See the next section, “How are basal and squamous cell skin cancers diagnosed?” for a more detailed description of what to look for.)

 

How are basal and squamous cell skin cancers treated?

This information represents the views of the doctors and nurses serving on the American Cancer Society’s Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.

The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.

Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don’t hesitate to ask him or her questions about your treatment options.

General treatment information

If you have been diagnosed with a non-melanoma skin cancer, your doctor will discuss your treatment options with you. Depending on your situation, you may have different types of doctors on your treatment team. Many basal and squamous cell cancers (as well as pre-cancers) are treated by dermatologists – doctors who specialize in treating skin diseases. If the cancer is more advanced, you may be treated by another type of doctor, such as a surgical oncologist, medical oncologist, or radiation oncologist.

Based on the stage of the cancer and other factors, your treatment options may include:

Fortunately, most basal cell and squamous cell carcinomas can be cured with fairly minor surgery or other types of local treatments.

The treatments described in the next few sections are those used for actinic keratosis, squamous cell carcinoma, basal cell carcinoma, and/or Merkel cell carcinoma. Other skin cancers, such as melanoma, lymphoma of the skin, Kaposi sarcoma, and other sarcomas are treated differently and are discussed in separate documents.

 

What should you ask your doctor about basal and squamous cell skin cancers?

As you cope with cancer and cancer treatment, you need to have honest, open discussions with your doctor. You should feel free to ask any question, no matter how small it might seem. Nurses, social workers, and other members of the treatment team may also be able to answer many of your questions. Here are some questions you might want to ask:

  • What type of skin cancer do I have?
  • Can you explain the different types of skin cancer?
  • Has my cancer spread beneath the skin? Has it spread to lymph nodes or other organs?
  • Are there other tests that need to be done before we can decide on treatment?
  • Are there other doctors I need to see?
  • How much experience do you have treating this type of cancer?
  • What are my treatment options? What do you recommend? Why?
  • Will I be okay if the cancer is just removed with no follow-up treatment?
  • What are the risks or side effects that I should expect?
  • Will I have a scar after treatment?
  • What are the chances of my cancer coming back with the treatment options we have discussed? What would we do if that happens?
  • What should I do to be ready for treatment?
  • What is my expected prognosis, based on my cancer as you view it?
  • What are my chances of developing another skin cancer?
  • Should I take special precautions to avoid sun exposure? What are the most important steps I can take to protect myself from the sun?
  • Are any of my family members at risk for skin cancer? What should I tell them to do?

Along with these sample questions, be sure to write down some of your own. For instance, you might want more information about recovery times so you can plan your work or activity schedule. Or you may want to ask about second opinions or about clinical trials for which you may qualify.

 

What will happen after treatment for basal and squamous cell skin cancers?

For most people with basal or squamous cell skin cancers, treatment will remove or destroy the cancer. Completing treatment can be both stressful and exciting. You may be relieved to finish treatment, but find it hard not to worry about cancer growing or coming back. (When cancer comes back after treatment, it is called recurrent cancer or a recurrence.) This is a very common concern in people who have had cancer.

It may take a while before your fears lessen. But it may help to know that many cancer survivors have learned to live with this uncertainty and are leading full lives. Our document called Living With Uncertainty: The Fear of Cancer Recurrence, gives more detailed information on this.

For small number of people with more advanced cancers, it may never go away completely. These people may get regular treatment with radiation therapy, chemotherapy, or other treatments to try to help keep the cancer in check. Learning to live with cancer that does not go away can be difficult and very stressful. It has its own type of uncertainty.

Follow-up care

If you have completed treatment, your doctors will still want to watch you closely and will likely recommend that you examine your skin once a month and protect yourself from the sun. Family members and friends can also be asked to watch for new lesions in areas that are hard to see.

If skin cancer does recur, it is most likely to happen in the first 5 years after treatment. People who have had skin cancer are also at high risk for developing another one in a different location, so close follow-up is important.

You should have follow-up exams as advised by your doctor. Your schedule for follow-up visits will depend on the type of cancer you had and on other factors. Different doctors may recommend different schedules.

  • For basal cell cancers, visits are often recommended about every 6 to 12 months.
  • For squamous cell cancers, visits are usually more frequent – often every 3 to 6 months for the first few years, followed by longer times between visits.

During your follow-up visits, your doctor will ask about symptoms and examine you for signs of recurrence or new skin cancers. For higher risk cancers, such as squamous cell cancers that had reached the lymph nodes, he or she may also order imaging tests such as CT scans. If skin cancer does recur, treatment options might depend on the size and location of the cancer, what treatments you’ve had before, and your overall health.

Follow-up is also needed to check for possible side effects of certain treatments. This is the time for you to ask your health care team any questions and to discuss any concerns you might have. Almost any cancer treatment can have side effects. Some may last for a few weeks to several months, but others can be permanent. Don’t hesitate to tell your cancer care team about any symptoms or side effects that bother you so they can help you manage them.

Seeing a new doctor

At some point after your cancer diagnosis and treatment, you may find yourself seeing a new doctor who does not know about your medical history. It is important that you be able to give your new doctor the details of your diagnosis and treatment. Make sure you have this information handy:

  • A copy of your pathology report(s) from any biopsies or surgeries
  • If you had surgery, a copy of your operative report(s)
  • If you were in the hospital, a copy of the discharge summary that doctors prepare when patients are sent home
  • If you had radiation therapy, a summary of the type and dose of radiation and when and where it was given
  • If you had chemotherapy or targeted therapy, a list of your drugs, drug doses, and when you took them

It is also important to keep your health insurance. Tests and doctor visits cost a lot, and even though no one wants to think of their cancer coming back, this could happen.

 

What’s new in research and treatment of basal and squamous cell skin cancers?

Research into the causes, prevention, and treatment of non-melanoma skin cancer is under way in many medical centers throughout the world.

Basic skin cancer research

Scientists have made a great deal of progress in recent years in learning how ultraviolet (UV) light damages DNA, and how this causes normal skin cells to become cancerous. Researchers are working to apply this new information to strategies for preventing and treating skin cancers.

Public education

Most skin cancers can be prevented. The best way to reduce the number of skin cancers and the pain and loss of life from this disease is to educate the public about skin cancer risk factors, prevention, and detection. It is important for health care professionals and skin cancer survivors to remind others about the dangers of excess UV exposure (from the sun and from man-made sources such as tanning beds) and about how easily they can protect their skin from UV radiation.

The American Academy of Dermatology (AAD) sponsors annual free skin cancer screenings throughout the country. Many local American Cancer Society offices work closely with AAD to provide volunteers for registration, coordination, and education efforts related to these free screenings. Look for information in your area about these screenings or call the American Academy of Dermatology for more information. Their phone number and Web address are listed in the “Additional resources” section of this document.

Preventing genital skin cancers

Squamous cell cancers that start in the genital region account for almost half of the deaths from this type of skin cancer. Many of these cancers may be related to infection with certain types of human papilloma virus (HPV), which can be spread through sexual contact. Limiting the number of sexual partners a person has and using safer sex practices such as wearing condoms may therefore help lower the risk of some of these cancers.

In recent years, vaccines have been developed to help protect against infection from some types of HPV. The main intent of the vaccines has been to reduce the risk of cervical cancer, but they may also lower the risk of other cancers that might be related to HPV, including some squamous cell cancers.

Chemoprevention

An area of active research is the field of chemoprevention (using drugs to reduce cancer risk). Chemoprevention is likely to be more useful for people at high risk of skin cancers, such as those with certain congenital conditions (such as basal cell nevus syndrome), a history of skin cancer, or those who have received organ transplants, rather than for people at average risk of skin cancer.

The most widely studied drugs so far are the retinoids, which are drugs related to vitamin A. They have shown some promise in reducing the risk of squamous cell cancers but can have side effects, including possibly causing birth defects. For this reason they are not widely used at this time, except in some people at very high risk. Further studies of retinoids are under way.

Other compounds are being looked at to reduce the risk of basal cell skin cancers in people at high risk. Drugs called hedgehog pathway inhibitors, which affect the activity of genes such as PTCH and SMO, may help some people with basal cell nevus syndrome. The targeted drug vismodegib (ErivedgeTM), taken daily as a pill, has been shown to lower the number of new basal cell cancers and shrink existing tumors in people with this syndrome. The drug does have some side effects, including taste loss and muscle cramps, which might make it hard for some people to take every day. Further research on this and similar drugs is under way.

Treatment

Local treatments

Current local treatments are successful for the vast majority of non-melanoma skin cancers. Still, even some small cancers can be hard to treat if they’re in certain areas. Newer forms of non-surgical treatment such as new topical drugs, photodynamic therapy, and laser surgery may help reduce scarring and other possible side effects of treatment. Studies are now under way to determine the best way to use these treatments, and to try to improve on their effectiveness.

Treating advanced disease

Most basal and squamous cell skin cancers are found and treated at a fairly early stage, but some may spread to other parts of the body. These cancers can often be hard to treat with current therapies such as radiation and chemotherapy.

Several studies are testing newer targeted drugs for advanced squamous cell cancers. Cells from these cancers often have too much of a protein called EGFR on their surfaces, which may help them grow. Drugs that target this protein, such as erlotinib (Tarceva) and gefitinib (Iressa), are now being tested in clinical trials. A drug that targets different cell proteins, known as dasatinib (Sprycel), is also being studied for advanced skin cancers.

It is very rare for basal cell cancers to reach an advanced stage, but when they do, these cancers can be hard to treat. Vismodegib (Erivedge), a new drug that targets the hedgehog signaling pathway in cells, may help some people (see “Targeted therapy for basal and squamous cell skin cancers.”).

 

By American Cancer Society