What are the three types of skin cancer

It doesn’t get as much attention as other skin cancers, but squamous cell cancer is common and serious.

From the Harvard Health Letter, May 2006

Summer’s the season for fun in the sun—but also for skin cancer. Of the three main types of skin cancer, melanoma is most deadly, and basal cell, most common. Squamous cell cancer falls in between. It’s three times as common as melanoma (some 200,000 new cases each year versus 62,000). Though not as common as basal cell (about one million new cases a year), squamous cell is more serious because it is likely to spread (metastasize). Treated early, the cure rate is over 90%, but metastases occur in 1%–5% of cases. After it has metastasized, it’s very difficult to treat.

What it looks like

Squamous cell cancer involves the runaway growth of keratinocytes, cells in the outermost layer of skin, which produce the protein keratin. Squamous means scaly; in 60%–80% of cases, the lesions emerge on or near scaly patches called actinic keratoses that develop from sun-damaged skin.

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This diagram shows the different layers of the skin. Basal cell carcinoma begins in the basal cell layer of the skin. Squamous cell carcinoma begins in the squamous layer of the skin. Melanoma begins in the melanocytes, which are the cells that make melanin, the pigment that gives skin its color.

The skin is the body’s largest organ. Skin has several layers, but the two main layers are the epidermis (upper or outer layer) and the dermis (lower or inner layer). Skin cancer begins in the epidermis, which is made up of three kinds of cells—

• Squamous cells: Thin, flat cells that form the top layer of the epidermis.
• Basal cells: Round cells under the squamous cells.
• Melanocytes: Cells that make melanin and are found in the lower part of the epidermis. Melanin is the pigment that gives skin its color. When skin is exposed to the sun, melanocytes make more pigment and cause the skin to darken.

Basal and squamous cell carcinomas are the two most common types of skin cancer. They begin in the basal and squamous layers of the skin, respectively. Both can usually be cured, but they can be disfiguring and expensive to treat.

Melanoma, the third most common type of skin cancer, begins in the melanocytes. Of all types of skin cancer, melanoma causes the most deaths because of its tendency to spread to other parts of the body, including vital organs.

Most cases of skin cancer are caused by overexposure to ultraviolet (UV) rays from the sun, tanning beds, or sunlamps. UV rays can damage skin cells. In the short term, this damage can cause a sunburn. Over time, UV damage adds up, leading to changes in skin texture, premature skin aging, and sometimes skin cancer. UV rays also have been linked to eye conditions such as cataracts.

Overview

What is skin cancer?

Skin cancer happens when skin cells grow and multiply in an uncontrolled, unorderly way.

Normally, new skin cells form when cells grow old and die or when they become damaged. When this process doesn’t work as it should, a rapid growth of cells (some of which may be abnormal cells) results. This collection of cells may be noncancerous (benign), which don’t spread or cause harm, or cancerous, which may spread to nearby tissue or other areas in your body if not caught early and treated.

Skin cancer is often caused by ultraviolet (UV) light exposure from the sun.

There are three main types of skin cancer:

• Basal cell carcinoma.
• Squamous cell carcinoma.
• Melanoma.

Basal cell carcinoma and squamous cell carcinoma are the most common types of skin cancer and are sometimes called “non-melanoma skin cancer.”

Melanoma is not as common as basal cell or squamous cell carcinomas but is the most dangerous form of skin cancer. If left untreated or caught in a late-stage, melanomas are more likely to spread to organs beyond the skin, making them difficult to treat and potentially life-limiting.

Fortunately, if skin cancer is identified and treated early, most are cured. This is why it is important to take a few safeguards and to talk with your healthcare provider if you think you have any signs of skin cancer.

How common is skin cancer?

Skin cancer is the most common cancer diagnosed in the U.S.

Other skin cancer facts:

• Around 20% of Americans develop skin cancer sometime in their life.
• Approximately 9,500 Americans are diagnosed with skin cancer every day.
• Having five or more sunburns in your life doubles your chance of developing melanoma. The good news is that the five-year survival rate is 99% if caught and treated early.
• Non-Hispanic white persons have almost a 30 times higher rate of skin cancer than non-Hispanic Black or Asian/Pacific Islander persons.
• Skin cancer in people with skin of color is often diagnosed in later stages when it’s more difficult to treat. Some 25% of melanoma cases in African Americans are diagnosed when cancer has spread to nearby lymph nodes.

Who is most at risk for skin cancer?

Although anyone can develop skin cancer, you’re at increased risk if you:

• Spend a considerable amount of time working or playing in the sun.
• Get easily sunburned; have a history of sunburns.
• Live in a sunny or high-altitude climate.
• Tan or use tanning beds.
• Have light-colored eyes, blond or red hair and fair or freckled skin.
• Have many moles or irregular-shaped moles.
• Have actinic keratosis (precancerous skin growths that are rough, scaly, dark pink-to-brown patches).
• Have a family history of skin cancer.
• Have had an organ transplant.
• Take medications that suppress or weaken your immune system.
• Have been exposed to ultraviolet light therapy for treating skin conditions such as eczema or psoriasis.

Where does skin cancer develop?

Skin cancer is most commonly seen in sun-exposed areas of your skin — your face (including your lips), ears, neck, arms, chest, upper back, hands and legs. However, it can also develop in less sun-exposed and more hidden areas of skin, including between your toes, under your fingernails, on the palms of your hands, soles of your feet and in your genital area.

Where, within the skin layers, does skin cancer develop?

Where skin cancer develops — specifically, in which skin cells — is tied to the types and names of skin cancers.

Most skin cancers begin in the epidermis, your skin’s top layer. The epidermis contains three main cell types:

• Squamous cells: These are flat cells in the outer part of the epidermis. They constantly shed as new cells form. The skin cancer that can form in these cells is called squamous cell carcinoma.
• Basal cells: These cells lie beneath the squamous cells. They divide, multiply and eventually get flatter and move up in the epidermis to become new squamous cells, replacing the dead squamous cells that have sloughed off. Skin cancer that begins in basal cells is called basal cell carcinoma.
• Melanocytes: These cells make melanin, the brown pigment that gives skin its color and protects your skin against some of the sun’s damaging UV rays. Skin cancer that begins in melanocytes is called melanoma.

Does skin cancer affect people with skin of color?

People of all skin tones can develop skin cancer. If you are a person of color, you may be less likely to get skin cancer because you have more of the brown pigment, melanin, in your skin.

Although less prevalent than in nonwhite people, when skin cancer does develop in people of color, it’s often found late and has a worse prognosis. If you’re Hispanic, the incidence of melanoma has risen by 20% in the past two decades. If you’re Black and develop melanoma, your five-year survival rate is 25% lower than it is for white people (67% vs 92%). Part of the reason may be that it develops in less typical, less sun-exposed areas (it develops mostly on palms of hands or soles of feet) and it’s often in late-stage when diagnosed.

Symptoms and Causes

What causes skin cancer?

The main cause of skin cancer is overexposure to sunlight, especially when it results in sunburn and blistering. Ultraviolet (UV) rays from the sun damage DNA in your skin, causing abnormal cells to form. These abnormal cells rapidly divide in a disorganized manner, forming a mass of cancer cells.

Another cause of skin cancer is frequent skin contact with certain chemicals, such as tar and coal.

Many other factors can increase your risk of developing skin cancer. See question, “Who is most at risk for skin cancer?”

What are the signs of skin cancer?

The most common warning sign of skin cancer is a change on your skin, typically a new growth, or a change in an existing growth or mole. The signs and symptoms of common and less common types of skin cancers are described below.

Basal cell carcinoma

Basal cell cancer is most commonly seen on sun-exposed areas of skin including your hands, face, arms, legs, ears, mouths, and even bald spots on the top of your head. Basal cell cancer is the most common type of skin cancer in the world. In most people, it’s slow growing, usually doesn’t spread to other parts of the body and is not life-threatening.

Signs and symptoms of basal cell carcinoma include:

• A small, smooth, pearly or waxy bump on the face, ears, and neck.
• A flat, pink/red- or brown-colored lesion on the trunk or arms and legs.
• Areas on the skin that look like scars.
• Sores that look crusty, have a depression in the middle or bleed often.

Squamous cell carcinoma

Squamous cell cancer is most commonly seen on sun-exposed areas of skin including your hands, face, arms, legs, ears, mouths, and even bald spots on the top of your head. This skin cancer can also form in areas such as mucus membranes and genitals.

Signs and symptoms of squamous cell carcinoma include:

• A firm pink or red nodule.
• A rough, scaly lesion that might itch, bleed and become crusty.

Melanoma

Melanoma can develop in any area of your body. It can even form on your eyes and internal organs. The upper back is a common site in men; legs are a common site in women. This is the most serious type of skin cancer because it can spread to other areas of your body.

Signs and symptoms of melanoma include:

• A brown-pigmented patch or bump.
• A mole that changes in color, size or that bleeds.

Thinking of the ABCDE rule tells you what signs to watch for:

• Asymmetry: irregular shape.
• Border: blurry or irregularly shaped edges.
• Color: mole with more than one color.
• Diameter: larger than a pencil eraser (6 mm).
• Evolution: enlarging, changing in shape, color, or size. (This is the most important sign.)

Be alert to pre-cancerous skin lesions that can develop into non-melanoma skin cancer. They appear as small scaly, tan or red spots, and are most often found on surfaces of the skin chronically exposed to the sun, such as the face and backs of the hands.

If you have a mole or other skin lesion that is causing you concern, make an appointment and show it to your healthcare provider. They will check your skin and may ask you to see a dermatologist and have the lesion further evaluated.

What are some of the lesser-known skin cancers?

Some of the less common skin cancers include the following:

Kaposi sarcoma

Kaposi sarcoma is a rare cancer most commonly seen in people who have weakened immune systems, those who have human immunodeficiency virus (HIV)/AIDS and people who are taking immunosuppressant medications who have undergone organ or bone marrow transplant.

Signs and symptoms of Kaposi sarcoma are:

• Blue, black, pink, red or purple flat or bumpy blotches or patches on your arms, legs and face. Lesions might also appear in your mouth, nose and throat.

Merkel cell carcinoma

Merkel cell carcinoma is a rare cancer that begins at the base of the epidermis, the top layer of your skin. This cancer starts in Merkel cells, which share of the features of nerve cells and hormone-making cells and are very close to the nerve ending in your skin. Merkel cell cancer is more likely to spread to other parts of the body than squamous or basal cell skin cancer.

Signs and symptoms of Merkel cell carcinoma are:

• A small reddish or purplish bump or lump on sun-exposed areas of skin.
• Lumps are fast-growing and sometimes open up as ulcers or sores.

Sebaceous gland carcinoma

Sebaceous gland carcinoma is a rare, aggressive cancer that usually appears on your eyelid. This cancer tends to develop around your eyes because there’s a large number of sebaceous glands in that area.

Signs and symptoms of sebaceous gland carcinoma are:

• A painless, round, firm, bump or lump on or slightly inside your upper or lower eyelid.

Dermatofibrosarcoma protuberans (DFSP)

DFSP is a rare skin cancer that begins in your dermis, the middle layer of your skin. It grows slowly, rarely spreads and has a high survival rate.

Signs and symptoms of DFSP are:

• A purple, pink, red, or brown scar-like bump or rough raised plaque on your skin.
• A birthmark-looking appearance in newborns and children.

Diagnosis and Tests

How is skin cancer diagnosed?

First, your dermatologist may ask you if you have noticed any changes in any existing moles, freckles or other skin spots or if you’ve noticed any new skin growths. Next, your dermatologist will examine all of your skin, including your scalp, ears, palms of your hands, soles of your feet, between your toes, around your genitals and between your buttocks.

If a skin lesion is suspicious, a biopsy may be performed. In a biopsy, a sample of tissue is removed and sent to a laboratory to be examined under a microscope by a pathologist. Your dermatologist will tell you if your skin lesion is skin cancer, what type you have and discuss treatment options.

Management and Treatment

How is skin cancer treated?

Treatment depends upon the stage of cancer. Stages of skin cancer range from stage 0 to stage IV. The higher the number, the more cancer has spread.

Sometimes a biopsy alone can remove all the cancer tissue if the cancer is small and limited to your skin’s surface only. Other common skin cancer treatments, used alone or in combination, include:

Cryotherapy

Cryotherapy uses liquid nitrogen to freeze skin cancer. The dead cells slough off after treatment. Precancerous skin lesions, called actinic keratosis, and other small, early cancers limited to the skin’s top layer can be treated with this method.

Excisional surgery

This surgery involves removing the tumor and some surrounding healthy skin to be sure all cancer has been removed.

Mohs surgery

With this procedure, the visible, raised area of the tumor is removed first. Then your surgeon uses a scalpel to remove a thin layer of skin cancer cells. The layer is examined under a microscope immediately after removal. Additional layers of tissue continue to be removed, one layer at a time, until no more cancer cells are seen under the microscope.

Mohs surgery removes only diseased tissue, saving as much surrounding normal tissue as possible. It’s most often used to treat basal cell and squamous cell cancers and near sensitive or cosmetically important areas, such as eyelids, ears, lips, forehead, scalp, fingers or genital area.

Curettage and electrodesiccation

The technique uses an instrument with a sharp looped edge to remove cancer cells as it scrapes across the tumor. The area is then treated with an electric needle to destroy any remaining cancer cells. This technique is often used for basal cell and squamous cell cancers and precancerous skin tumors.

Chemotherapy and immunotherapy

Chemotherapy uses medications to kill cancer cells. Anticancer medications can be applied directly on the skin (topical chemotherapy) if limited to your skin’s top layer or provided through pills or an IV if cancer has spread to other parts of your body. Immunotherapy uses your own body’s immune system to kill cancer cells.

Radiation therapy

Radiation therapy is a form of cancer treatment that uses radiation (strong beams of energy) to kill cancer cells or keep them from growing and dividing.

Photodynamic therapy

In this therapy, your skin is coated with medication and a blue or red fluorescent light then activates the medication. Photodynamic therapy destroys precancerous cells while leaving normal cells alone.

Prevention

Can skin cancer be prevented?

In most cases, skin cancer can be prevented. The best way to protect yourself is to avoid too much sunlight and sunburns. Ultraviolet (UV) rays from the sun damage your skin, and over time this may lead to skin cancer.

Ways to protect yourself from skin cancer include:

• Use a broad-spectrum sunscreen with a skin protection factor (SPF) of 30 or higher. Broad-spectrum sunscreens protect against both UV-B and UV-A rays. Apply the sunscreen 30 minutes before you go outside. Wear sunscreen every day, even on cloudy days and during the winter months.
• Wear hats with wide brims to protect your face and ears.
• Wear long-sleeved shirts and pants to protect your arms and legs. Look for clothing with an ultraviolet protection factor label for extra protection.
• Wear sunglasses to protect your eyes. Look for glasses that block both UV-B and UV-A rays.
• Use a lip balm with sunscreen.
• Avoid the sun between 10 a.m. and 4 p.m.
• Avoid tanning beds. If you want a tanned look, use a spray-on tanning product.
• Ask your healthcare provider or pharmacist if any of the medications you take make your skin more sensitive to sunlight. Some medications known to make your skin more sensitive to the sun include tetracycline and fluoroquinolone antibiotics, tricyclic antibiotics, the antifungal agent griseofulvin, and statin cholesterol-lowering drugs.
• Check all the skin on your body and head for any changes in size, shape or color of skin growths or the development of new skin spots. Don’t forget to check your scalp, ears, the palms of your hands, soles of your feet, between your toes, your genital area and between your buttocks. Use mirrors and even take pictures to help identify changes in your skin over time. Make an appointment with your dermatologist if you notice any changes in a mole or other skin spot.

Outlook / Prognosis

What is the outlook for people with skin cancer?

Nearly all skin cancers can be cured if they are treated before they have a chance to spread. The earlier skin cancer is found and removed, the better your chance for a full recovery. Ninety percent of those with basal cell skin cancer are cured. It is important to continue following up with a dermatologist to make sure cancer does not return. If something seems wrong, call your doctor right away.

Most skin cancer deaths are from melanoma. If you are diagnosed with melanoma:

• The five-year survival rate if it’s detected before it spreads to the lymph nodes is 99%.
• The five-year survival rate if it has spread to nearby lymph nodes is 66%.
• The five-year survival rate if it has spread to distant lymph nodes and other organs is 27%.

When should I see my healthcare provider?

Make an appointment to see your healthcare provider or dermatologist as soon as you notice:

• Any changes to your skin or changes in the size, shape or color of existing moles or other skin lesions.
• The appearance of a new growth on your skin.
• A sore that doesn’t heal.
• Spots on your skin that are different from others.
• Any spots that change, itch or bleed.

Your provider will check your skin, take a biopsy (if needed), make a diagnosis and discuss treatment. Also, see your dermatologist annually for a full skin review.

What questions should I ask my healthcare provider?

Questions to ask your dermatologist may include:

• What type of skin cancer do I have?
• What stage is my skin cancer?
• What tests will I need?
• What’s the best treatment for my skin cancer?
• What are the side effects of that treatment?
• What are the potential complications of this cancer and the treatment for it?
• What outcome can I expect?
• Do I have an increased risk of additional skin cancers?
• How often should I be seen for follow-up checkups?

Frequently Asked Questions

How does skin cancer become a life-threatening cancer?

You may wonder how cancer on the surface of your skin becomes a life-threatening cancer. It seems logical to think you could just scrape off the skin with the cancer cells or even remove the cancerous skin lesion with a minor skin surgery and that’s all that would be needed. These techniques are successfully used if cancer is caught early.

But if skin cancer isn’t caught early, something that’s “just on my skin” can grow and spread beyond the immediate area. Cancer cells break away and travel through the bloodstream or lymph system. The cancer cells settle in other areas of your body and begin to grow and develop into new tumors. This travel and spread is called metastasis.

The type of cancer cell where cancer first started — called primary cancer — determines the type of cancer. For example, if malignant melanoma metastasized to the lungs, the cancer would still be called malignant melanoma. This is how that superficial skin cancer can turn into life-threatening cancer.

Why does skin cancer occur in more non-sun-exposed body areas in people of color?

Scientists don’t fully know why people of skin with color develop cancer in non-sun-exposed areas, such as their hands and feet. They think that the sun is less of a factor though. However, dermatologists still see plenty of UV sunlight-induced melanomas and squamous cell skin cancer in people of color, in skin tones ranging from fair to very dark.

Are all moles cancerous?

Most moles are not cancerous. Some moles are present at birth, others develop up to about age 40. Most adults have between 10 and 40 moles.

In rare cases, a mole can turn into melanoma. If you have more than 50 moles, you have an increased chance of developing melanoma.

A note from Cleveland Clinic

Your skin is the largest organ in your body. It needs as much attention as any other health concern. What may seem like an innocent cosmetic imperfection, may not be. Performing regular skin self-checks is important for everyone and is especially important if you are a person at increased risk of skin cancer. Skin cancer is also color-blind. If you are a person of color, skin cancer can happen to you. Check your skin every month for any changes in skin spots or any new skin growths. Consider taking “skin selfies” so you can easily see if spots change over time. If you’re a person of color, be sure to check areas more prone to cancer development, such as the palms of your hands, soles of your feet, between your toes, your genital area and under your nails. Takes steps to protect your skin. Always wear sunscreen with SPF of at least 30 every day of the year. Wear UV-A/UV-B protective sunglasses, wide-brimmed hats and long-sleeve shirts and pants. See your dermatologist at least once a year for a professional skin check.

What is the most serious types of skin cancer?

Which cancer is the least aggressive type of skin cancer?

What are three types of skin cancers and how are they different?

What is the difference between basal cell and squamous cell carcinoma?