What to Know About Skin Cancer
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Medically reviewed by Casey Gallagher, MD
Skin cancer is cancer that develops in skin cells. It occurs when the DNA that controls cell growth is damaged.
The most common cause of skin cancer is ultraviolet rays from the sun or tanning beds. While skin cancer can occur anywhere, most skin cancers appear on areas of the skin that are exposed to the sun, like your neck and face.
This article describes skin cancer types, symptoms, causes, diagnosis, and treatment. It also includes ways to help prevent the disease.
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Types of Skin Cancer
Skin cancers are named for the type of cells that become cancerous. Skin cancer develops when cells in your epidermis (the outermost layer of your skin) become damaged and grow abnormally fast.
There are four main types of skin cancer.
Basal Cell Carcinoma
Basal cell carcinoma is cancer that begins in your skin's basal cells in the middle layer of your epidermis. It ranks as the most common type of skin cancer and the most common form of all cancers.
Basal cell carcinomas are often found in areas of the skin that are exposed to the sun, like your face, neck, or hands. If untreated, a basal cell carcinoma tumor can destroy surrounding tissues, causing a large defect.
Most basal cell carcinomas are slow-growing. They can usually be cured without causing damage if they are caught and treated early. This type of cancer rarely metastasizes (spreads) from the original tumor site to other body parts. It is seldom life-threatening.
Squamous Cell Carcinoma
Squamous cell carcinoma is cancer in your skin's squamous cells, the thin, flat cells located in the uppermost layer of your epidermis. It ranks as the second most common form of skin cancer.
Squamous cell carcinomas are often found in sun-exposed areas. They can appear as a wartlike growth or a sore that is rough and crusted.
Squamous cell carcinomas are fast-growing and sometimes metastasize. This type of cancer is highly treatable when diagnosed early.
Melanoma
Melanoma is a cancer that forms from melanocytes. These cells are found in the lower part of your epidermis. They are the skin cells that produce melanin, which gives your skin its color. It is less common than other types of cancer.
Melanomas often appear on the trunk (chest and back) of men and the legs of women. They can also develop on your neck and face.
Melanoma is dangerous because it is more likely to spread to other parts of your body if it is not treated early. Without care, melanoma can become difficult to treat and potentially deadly.
Your natural skin tone can affect the appearance of melanoma. If you have darker skin, look for the following:
A dark spot, growth, or darker patch of skin that is growing, bleeding, or changing in any way
A sore that won’t heal (or heals and returns)
A patch of skin that feels dry and rough
A dark line underneath or around a fingernail or toenail
Merkel Cell Carcinoma
Merkel cell carcinoma begins in the Merkel cells of the skin's epidermis. They are connected to your nerves, sending messages about touch to your brain.
Merkel cell carcinoma can appear as firm, painless sores or bumps in sun-exposed areas of your body. They can sometimes open up and form sores or ulcers.
Merkel cell carcinomas are very dangerous because they grow so quickly and are more likely to affect other parts of your body.
Learn More:What Are the Different Types of Skin Cancer?
Skin Cancer Symptoms: What Are the Signs?
Skin cancer symptoms vary from person to person. How your skin looks depends on your skin tone, the type and size of the skin cancer, and its location on your body.
The first signs of skin cancer can be mistaken for a common mole, pimple, or wart. You can reduce your risk of skin cancer progressing with treatment. Consult a dermatologist if you notice new, unusual, or changing spots that itch, change, or bleed.
The most common signs of skin cancer are:
A new spot on your skin
Noticeable changes in the size, color, or shape of an existing sore or spot on your skin
A skin growth that resembles a wart
A painful or itchy spot on your skin that doesn't change
A nonhealing spot on your skin that bleeds or becomes crusty
A skin sore or growth that has a raised border and central crusting or bleeding
A red, scaly, or rough spot on your skin
A scar-like growth that lacks a well-defined border
The following symptoms occur with certain types of skin cancers:
Basal cell carcinoma rarely causes pain when it is forming. It can appear as any of the following:
A small, smooth, pale patches of skin
A small, pink, pearly skin bump
A waxy or pearly lump on your skin
A red patch or irritated area
A small, pink, pearly skin bump
A yellow or white scar-like area
A smooth growth with a dent or dimple in the middle
A bleeding or oozing score
A sore that crusts over with a scab
Squamous cell carcinomas typically have the following characteristics:
A scaly red patch
An open sore
A rough, thickened, or wartlike area of skin
A raised growth with a central depression
A sore that crusts over, itches, or bleeds
Melanoma can often be detected by looking for skin growths using the ABCDE guide:
A is for asymmetry: Most melanomas are asymmetrical (two halves that are not the same).
B is for border: Melanoma borders tend to have notched or scalloped and poorly defined edges.
C is for color: Melanomas tend to be different shades of brown, tan, or black, or have areas of white, red, or blue.
D is for diameter or dark: Melanomas tend to have a diameter the size of a pencil eraser (about one-quarte inch in diameter) or larger.
E is for evolving: Melanomas evolve in size, shape, color, or elevation of a spot on your skin.
Merkel cell skin cancer often looks harmless and has the following characteristics:
Fast-growing
Pink, red, or purple color
Painless
Growth on the head or neck
Onset after age 50
Learn More:Symptoms of Skin Cancer
What Causes Skin Cancer?
Over 80% of skin cancers are caused by excessive exposure to ultraviolet (UV) radiation. UV radiation comes from sources such as the sun, tanning beds, and tanning lamps.
UV light damages the DNA inside our skin whenever it comes in contact with it. The longer time and severity of sun exposure increase your risk of skin cancer. The more sunburns you get, the more damage occurs. This damage accumulates over time, increasing your risk of having the genetic mutations that cause skin cancer.
Having certain factors can also increase your chances of having skin cancer:
A previous case of nonmelanoma cancer
A family history of skin cancer
A large number of moles and freckles
Naturally red or blond hair
Pale skin that easily burns and rarely tans
Blue, green, or light-colored eyes
A weakened immune system due to medication or certain medical conditions
Past treatment with radiation
Exposure to arsenic
History of sunburns
Learn More:Causes and Risk Factors of Skin Cancer
Testing to Diagnose Skin Cancer
Diagnosing cancer involves the following procedures that examine your skin:
Physical exam: During a physical exam of your body, your healthcare provider checks for general signs of health and disease. This includes checking for signs of lumps and sores. Medical and family histories are also taken to determine your risk of skin cancer and other diseases.
Skin exam: A skin exam is a detailed visual examination of the skin bumps or spots that appear abnormal in size, color, texture, or shape.
Skin biopsy: A skin biopsy involves removing all or part of a skin bump or spot that looks abnormal. The tissue is viewed under a microscope to check for signs of cancer. One of the following types of skin biopsies may be used:
Shave biopsy: Uses a sterile razor blade to shave off the abnormal-looking growth
Punch biopsy: Uses a special instrument called a punch or trephine (a hollow, circular scalpel) to remove a circle of tissue from an abnormal-looking growth
Incisional biopsy: Uses a scalpel to remove part of an abnormal-looking growth
Excisional biopsy: Uses a scalpel to remove the entire abnormal-looking growth
The American Joint Committee on Cancer developed the following system for describing skin cancer stages and disease progression:
Stage 0: Also known as carcinoma in situ ( in the original place), skin cancer is limited to the epidermis in this stage.
Stage 1: The tumor is smaller than 2 centimeters and has not spread to nearby lymph nodes or other organs. There are one or fewer risk factors.
Stage 2: The tumor is wider than 2 centimeters and has not spread to nearby lymph nodes or other organs. There are two or more risk factors.
Stage 3: The tumor has spread into nearby facial bones or one lymph node. It has not spread to other organs.
Stage 4: The tumor is of any size and has spread to one or more lymph nodes. The disease may have spread to bones and other distant organs.
Skin Cancer Screening
Skin cancer screening involves looking for signs of skin cancer before you have symptoms. This can increase your chances of finding the disease as soon as possible and starting treatment in the early stages of the disease when it is most effective.
The Skin Cancer Foundation recommends an annual full-body professional skin exam by a dermatologist. You should have these exams more often if you have a high risk of skin cancer.
A typical skin exam lasts about 10 minutes. It involves a head-to-toe visual exam of your skin. Special attention is given to hard-to-see areas like your back, scalp, and behind your ears. Your dermatologist may use a dermoscope, a tool that helps them visualize your epidermis and its hidden layers. A biopsy of any suspicious areas may be taken during this exam.
Performing a regular self-exam of your skin can help you notice any new, changing, or unusual skin growths between skin exams. The American Academy of Dermatology Association recommends the following procedure for performing a skin self-exam:
Examine the front and back of your body using a full-length mirror.
Examine your palms, forearms, and underarms.
Examine your legs, between your toes, and the soles of your feet.
Examine your neck and scalp with a hand mirror.
Examine your back and buttocks with a hand mirror.
Learn More:How Skin Cancer Is Diagnosed
Skin Cancer Treatment
The skin cancer treatment you receive depends on the type of cancer, the stage, the size and location of the tumor, and its features. One or more of the following treatments may be used:
Radiation therapy: The use of high-energy X-rays or other particles are administered externally to kill cancer cells. It may be given internally using seeds that are implanted in your body.
Targeted drug therapy: Targeted drug therapies focus on the specific molecular pathways involved in the abnormal growth of skin cancer cells, which may halt their progression.
Chemotherapy: Chemotherapy uses drugs to kill abnormal cancer cells. It can be administered topically, intravenously, or via injection.
Photodynamic therapy: Photodynamic therapy combines photosensitive drugs with light to kill cancer cells.
Immunotherapy: Immunotherapy helps your body's immune system find and attack cancer cells. It uses human-made or natural materials to target, boost, or restore the function of your immune system.
Laser surgery: Laser surgery uses a laser beam (a narrow beam of intense light) as a knife to cut tissue or remove a surface lesion or tumor.
Dermabrasion: This procedure removes the top layer of skin using small particles or a rotating wheel to rub away skin cells.
Surgery:
Simple excision is the surgical removal of a tumor and a small area surrounding it.
Shave excision is the surgical removal of an abnormal area with a small blade.
Cryosurgery uses an instrument to freeze and destroy abnormal tissue.
Curettage and electrodesiccation involves using a scalpel to shave off the lesion (curettage), then burns (electrodesiccation) the surrounding tissue to stop bleeding.
Mohs surgery (microscopically controlled surgery) is a highly specialized surgical technique that involves cutting away thin layers of the skin and checking each layer for cancer under a microscope until a layer without cancer cells is reached.
Side Effects of Skin Cancer Treatment
The side effects of skin cancer treatment vary by type of treatment and your unique response to treatment.
The most common side effect of skin cancer treatment is fatigue. Pain can also occur during the healing process.
Common side effects of skin cancer treatment include the following:
Chemotherapy:
Low blood counts
Nausea and vomiting
Peripheral neuropathy (damage to the nerves that control sensation in your hands and feet)
Skin pigmentation changes
Dark and cracked nails
Temporary hair loss (alopecia)
Photosensitivity (minor rash or sunburn easily)
Photodynamic Therapy:
Burning
Itching or tingling
Rash or redness
Immunotherapy:
Redness, itching, flaking, or bleeding skin
Colitis
Targeted Therapy:
Headache
Radiation Therapy:
Pruritus (dry, itchy, and peeling skin)
Possible increased risk of second cancer development
Learn More:How Skin Cancer Is Treated
How to Prevent Skin Cancer
While you can't completely prevent skin cancer, the following strategies may help reduce your risk of having the disease:
Avoid being in the sun between 10 a.m. and 4 p.m., when UV rays are the strongest. Seek shade if you are outside during these times.
Take all precautions to avoid getting sunburned.
Avoid tanning in the sun or using UV tanning beds.
Cover all your skin with clothing, including a broad-brimmed hat and UV-blocking sunglasses, when you are outside during the day.
Use a broad-spectrum (UVA/UVB) sunscreen with a sun protection factor (SPF) of 15 or higher daily. If you will be outside for an extended time, use a water-resistant, broad-spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.
Apply sunscreen liberally to cover all exposed areas of your skin. Reapply as directed, especially when sweating or swimming.
Keep newborns out of the sun since it is not advised to use sunscreen on babies this young. Use sunscreen on babies over the age of 6 months.
Examine your from skin head to toe every month to identify signs of skin cancer as early as possible.
Visit a dermatologist annually (more frequently if you have known risk factors) for a professional skin exam.
Outlook for Skin Cancer
The outlook, or prognosis, for skin cancer varies based on the type of skin cancer. Other factors like the stage and extent of skin cancer, its spread to other areas, and the way it reacts to treatment, also affect your prognosis. Personal characteristics like your age and other medical conditions can also impact the predicted outcomes of your disease.
Your healthcare provider forms a prognosis based on your chances of recovery or survival from skin cancer. This outlook is calculated on the experiences of large groups of people over many years, not individual cases. Your experience with skin cancer can differ from the prognosis you receive.
The outlook for skin cancers varies by type of disease to reflect the following five-year survival rates:
Basal Cell Carcinoma:
Five-year survival rate of 100% when the disease has not spread
Generally, poor survival rates when this disease spreads to other areas of your body
Squamous Cell Carcinoma:
Five-year survival rate of 99% when the disease has not spread
Survival rates that decrease to a three-year survival rate of less than 50% with spread to other areas of your body
Melanoma:
Five-year survival rate of 99% when the skin cancer has not spread
Generally, very poor five-year survival rates when the disease spreads
Merkel Cell Carcinoma:
Five-year survival rate of 75% when the disease has not spread
Five-year survival rate of 61% when cancer spreads to nearby lymph nodes, with typically poor five-year survival rates when cancer spreads to distant parts of your body
Learn More:How Deadly Is Skin Cancer?
Summary
Skin cancer is cancer that begins in skin cells. Four major types of skin cancer are based on the type of skin cells that cause the disease.
Exposure to UV rays in sunlight and tanning beds is the main cause of all cancer types. Risk factors for skin cancer include being fair-skinned and exposure to cancer radiation.
Most cases of skin cancer are treatable when found early. The challenge in finding skin cancer is that everyone's symptoms can differ based on skin tone and texture.
Routine self-exams and regular skin exams can help find skin cancer in its early stages, when treatment can achieve the best outcomes.
