Skin cancer is the most common form of cancer in the United States. The two most common types are basal cell cancer and squamous cell cancer. They usually form on the head, face, neck, hands, and arms. Another type of skin cancer, melanoma, is more dangerous but less common.

Anyone can get skin cancer, but it is more common in people who

• Spend a lot of time in the sun or have been sunburned
• Have light-colored skin, hair and eyes
• Have a family member with skin cancer
• Are over age 50

You should have your doctor check any suspicious skin markings and any changes in the way your skin looks. Treatment is more likely to work well when cancer is found early. If not treated, some types of skin cancer cells can spread to other tissues and organs. Treatments include surgery, radiation therapy, chemotherapy, photodynamic therapy (PDT), and biologic therapy. PDT uses a drug and a type of laser light to kill cancer cells. Biologic therapy boosts your body's own ability to fight cancer.

General Information About Skin Cancer

KEY POINTS

• Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.
• Different types of cancer start in the skin.
• Skin color and being exposed to sunlight can increase the risk of basal cell carcinoma and squamous cell carcinoma of the skin.
• Basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis often appear as a change in the skin.
• Tests or procedures that examine the skin are used to diagnose basal cell carcinoma and squamous cell carcinoma of the skin.
• Certain factors affect prognosis (chance of recovery) and treatment options.

Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.

The skin is the body’s largest organ. It protects against heat,sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The 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 foundin the lower part of the epidermis. Melanin is the pigmentthat gives skin its natural color. When skin is exposed to the sun, melanocytesmake more pigment and cause the skin to darken.

Skin cancer can occur anywhere on the body, but it is most common in skin that is often exposed to sunlight, such as the face, neck, and hands.

Different types of cancer start in the skin.

Skin cancer may form in basal cells or squamous cells. Basal cell carcinoma and squamous cell carcinoma are the most common types of skin cancer. They are also called nonmelanoma skin cancer. Actinic keratosis is a skin condition that sometimes becomes squamous cell carcinoma.

Melanoma is less common than basal cell carcinoma or squamous cell carcinoma. It is more likely to invade nearby tissues and spread to other parts of the body.

This summary is about basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis.

Basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis often appear as a change in the skin.

Not all changes in the skin are a sign of basal cell carcinoma, squamous cell carcinoma of the skin, or actinic keratosis. Check with your doctor if you notice any changes in your skin.

Signs of basal cell carcinoma and squamous cell carcinoma of the skin include the following:

• A sore that does not heal.
• Areas of the skin that are:
  • Raised, smooth, shiny, and look pearly.
  • Firm and look like a scar, and may be white, yellow, or waxy.
  • Raised and red or reddish-brown.
  • Scaly, bleeding, or crusty.

Basal cell carcinoma and squamous cell carcinoma of the skin occur most often in areas of the skin exposed to the sun, such as the nose, ears, lower lip, or top of the hands.

Signs of actinic keratosis include the following:

• A rough, red, pink, or brown, scaly patch on the skin that may be flat or raised.
• Cracking or peeling of the lower lip that is not helped by lip balm or petroleum jelly.

Actinic keratosis occurs most commonly on the face or the top of the hands.

Certain factors affect prognosis (chanceof recovery) and treatment options.

The prognosis for squamous cell carcinoma of the skin depends mostly on the following:

• Stage of the cancer.
• Whether the patient is immunosuppressed.
• Whether the patient uses tobacco.
• The patient's general health.

Treatment options for basal cell carcinoma and squamous cell carcinoma of the skin depend on the following:

• The type of cancer.
• The stage of the cancer, for squamous cell carcinoma.
• The size of the tumor and what part of the body it affects.
• The patient’s general health.

One of the most talked about diseases is skin cancer. Cancer is a broad term that describes diseases caused by abnormal cells in the body dividing uncontrollably. Most cancers are identified by the organ or tissue in which the cancer originates. One common form of cancer is skin cancer. The Skin Cancer Foundation reports that one in five Americans will experience some type of skin cancer in their lifetime. The degradation of the ozone layer in the atmosphere and the resulting increase in exposure to UV radiation has contributed to its rise. Overexposure to UV radiation damages DNA, which can lead to the formation of cancerous lesions. Although melanin offers some protection against DNA damage from the sun, often it is not enough. The fact that cancers can also occur on areas of the body that are normally not exposed to UV radiation suggests that there are additional factors that can lead to cancerous lesions.

In general, cancers result from an accumulation of DNA mutations. These mutations can result in cell populations that do not die when they should and uncontrolled cell proliferation that leads to tumors. Although many tumors are benign (harmless), some produce cells that can mobilize and establish tumors in other organs of the body; this process is referred to as metastasis. Cancers are characterized by their ability to metastasize.

Basal Cell Carcinoma

Basal cell carcinoma is a form of cancer that affects the mitotically active stem cells in the stratum basale of the epidermis. It is the most common of all cancers that occur in the United States and is frequently found on the head, neck, arms, and back, which are areas that are most susceptible to long-term sun exposure. Although UV rays are the main culprit, exposure to other agents, such as radiation and arsenic, can also lead to this type of cancer. Wounds on the skin due to open sores, tattoos, burns, etc. may be predisposing factors as well. Basal cell carcinomas start in the stratum basale and usually spread along this boundary. At some point, they begin to grow toward the surface and become an uneven patch, bump, growth, or scar on the skin surface (Figure 5.18). Like most cancers, basal cell carcinomas respond best to treatment when caught early. Treatment options include surgery, freezing (cryosurgery), and topical ointments (Mayo Clinic 2012).

Figure 5.18 Basal Cell Carcinoma Basal cell carcinoma can take several different forms. Similar to other forms of skin cancer, it is readily cured if caught early and treated. (credit: John Hendrix, MD)

Squamous Cell Carcinoma

Squamous cell carcinoma is a cancer that affects the keratinocytes of the stratum spinosum and presents as lesions commonly found on the scalp, ears, and hands (Figure 5.19). It is the second most common skin cancer. The American Cancer Society reports that two of 10 skin cancers are squamous cell carcinomas, and it is more aggressive than basal cell carcinoma. If not removed, these carcinomas can metastasize. Surgery and radiation are used to cure squamous cell carcinoma.

Figure 5.19 Squamous Cell Carcinoma Squamous cell carcinoma presents here as a lesion on an individual’s nose. (credit: the National Cancer Institute)

Melanoma

A melanoma is a cancer characterized by the uncontrolled growth of melanocytes, the pigment-producing cells in the epidermis. Typically, a melanoma develops from a mole. It is the most fatal of all skin cancers, as it is highly metastatic and can be difficult to detect before it has spread to other organs. Melanomas usually appear as asymmetrical brown and black patches with uneven borders and a raised surface (Figure 5.20). Treatment typically involves surgical excision and immunotherapy.

Figure 5.20 Melanoma Melanomas typically present as large brown or black patches with uneven borders and a raised surface. (credit: the National Cancer Institute / Centers for Disease Control)

Doctors often give their patients the following ABCDE mnemonic to help with the diagnosis of early-stage melanoma. If you observe a mole on your body displaying these signs, consult a doctor.

• Asymmetry – the two sides are not symmetrical
• Borders – the edges are irregular in shape
• Color – the color is varied shades of brown or black
• Diameter – it is larger than 6 mm (0.24 in)
• Evolving – its shape has changed

Some specialists cite the following additional signs for the most serious form, nodular melanoma:

• Elevated – it is raised on the skin surface
• Firm – it feels hard to the touch
• Growing – it is getting larger

A malignant skin neoplasm that seldom metastasizes but has potentialities for local invasion and destruction. Clinically it is divided into types: nodular, cicatricial, morphaic, and erythematoid (pagetoid). They develop on hair-bearing skin, most commonly on sun-exposed areas. Approximately 85% are found on the head and neck area and the remaining 15% on the trunk and limbs.

Basal Cell

• A small raised bump that looks smooth, shiny, and translucent.
• A small, pink, crater-like growth with a raised, rolled border and an indentation in the center.
• A scar-like area that is white, yellow, or waxy.
• Reddish, irritated patches of skin.
• A sore that does not heal.
• Can usually be removed by excision or topical treatments.
• If diagnosed and treated early, basal cell cancers can be cured.

A carcinoma derived from stratified SQUAMOUS EPITHELIAL CELLS. It may also occur in sites where glandular or columnar epithelium is normally present.

Squamous Cell Carcinoma

• Crusty, warty appearance.
• A raised growth with a depression in the center.
• Scaly, red patch area.
• A sore that does not heal.
• Can usually be removed by excision or topical treatments.
• If diagnosed and treated early, squamous cell cancers can be cured.

A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world.

Melanoma

Changes in the size, shape, or color of moles.

• Dark mole-like appearance.
• Flat or slightly elevated discolored patch (tan, brown, red, black, blue, or white).
• Change on the skin:
• New spot developing.
• Change in size, color, or shape of existing spot or mole.
• Malignant melanoma carries significant, even fatal implications.
• Incidence of melanoma has been steadily rising, affecting people of all ages.

Symptoms

In particular, watch for:

• Irregular borders on moles (ragged, notched, or blurred edges).
• Moles that are not symmetrical (one half doesn’t match the other).
• Colors that are not uniform throughout.
• Moles that are bigger than a pencil eraser.
• Sores that bleed and do not heal.
• Itchy or painful moles.
• Red patches or lumps.
• New moles.

Anyone can get skin cancer, but people with certain characteristics are at greater risk—

• A lighter natural skin color.
• Skin that burns, freckles, reddens easily, or becomes painful in the sun.
• Blue or green eyes.
• Blond or red hair.
• Certain types and a large number of moles.
• A family history of skin cancer.
• A personal history of skin cancer.
• Older age.

Exposure to UV Rays

Regardless of whether you have any of the risk factors listed above, reducing your exposure to ultraviolet (UV) rays can help keep your skin healthy and lower your chances of getting skin cancer in the future. Most people get at least some UV exposure from the sun when they spend time outdoors. Making sun protection an everyday habit will help you to enjoy the outdoors safely, avoid getting a sunburn, and lower your skin cancer risk.

Do You Have a Sunburn?

Learn the symptoms of sunburn, get first aid tips, and find out when to seek medical care.

Indoor tanning (using a tanning bed, booth, sunbed, or sunlamp to get tan) exposes users to high levels of UV radiation for the purpose of getting a tan. When UV rays reach the skin’s inner layer, the skin makes more melanin. Melanin is the pigment that colors the skin. It moves toward the outer layers of the skin and becomes visible as a tan.

A tan does not indicate good health. A tan is your skin’s response to injury, because skin cells signal that they have been hurt by UV rays by producing more pigment. Any change in skin color after UV exposure (whether it is a tan or a burn) is a sign of injury, not health. Over time, too much exposure to UV rays can cause skin cancers including melanoma (the deadliest type of skin cancer), basal cell carcinoma, and squamous cell carcinoma. UV exposure can also cause cataracts and cancers of the eye (ocular melanoma). Every time you tan, you increase your risk of getting skin cancer.

A change in your skin is the most common sign of skin cancer. This could be a new growth, a sore that doesn’t heal, or a change in a mole. Not all skin cancers look the same.

For melanoma specifically, a simple way to remember the warning signs is to remember the A-B-C-D-Es of melanoma—

• “A” stands for asymmetrical. Does the mole or spot have an irregular shape with two parts that look very different?
• “B” stands for border. Is the border irregular or jagged?
• “C” is for color. Is the color uneven?
• “D” is for diameter. Is the mole or spot larger than the size of a pea?
• “E” is for evolving. Has the mole or spot changed during the past few weeks or months?

Talk to your doctor if you notice changes in your skin such as a new growth, a sore that doesn’t heal, a change in an old growth, or any of the A-B-C-D-Es of melanoma.

Skin cancer is the most common form of cancer in the U.S. It's also largely preventable. Here is information from the National Cancer Institute about common risk factors and types of skin cancer.

What causes it:

The disease forms in tissues of the skin and is usually caused by the sun or ultraviolet (UV) rays. UV rays are an invisible type of radiation that comes from the sun, tanning beds, and sun lamps. The rays can change skin cells if you are exposed to them too much.

Risk factors:

• Being exposed to natural or fake sunlight over long periods of time.
• Having a fair complexion. However, people of all skin colors can get skin cancer.
• A history of sunburns.
• Having a personal or family history of skin cancer.

Where it happens:

Skin cancer can happen anywhere on your body, but it is most common in skin that is often exposed to sunlight, such as the face, neck, and hands. When checking for skin cancer, your health care provider will look for moles or birthmarks that look abnormal in color, size, shape, or texture.

The "ABCDE" rule

The "ABCDE" rule is a good way to spot early melanoma. Look for changes in moles, birthmarks, and other areas of the skin:

• Asymmetry. The shape of one half does not match the other half.
• Border that is irregular. The edges are often ragged, notched, or blurred in outline. The color may spread into the surrounding skin.
• Color that is uneven. Shades of black, brown, and tan may be present. Areas of white, gray, red, pink, or blue may also be seen.
• Diameter. There is a change in size, usually an increase. Melanomas can be tiny, but most are larger than 6 millimeters (about 1/4 inch) wide.
• Evolving. The mole has changed over the past few weeks or months.

Common types of skin cancer:

The three most common types are found on the top layer of the skin: basal cell, squamous cell, and melanoma. Exposure to the sun and ultraviolet rays are the leading cause of these types of cancer.

• Basal cell cancer grows in areas of your body that are more exposed to the sun, such as your head and neck. They grow slowly, rarely spread, and are the least likely to cause death.
• Squamous cell cancer is found on the outer layer of the skin, usually on your face, ears, neck, lips, and backs of your hands; the areas of your body that get the most sun. The cells can spread to other places in your body, but if caught in time, can be removed and are not deadly.
• Melanoma cancer is much less common than basal cell and squamous cell cancers. However, the cancer cells are more likely to grow and spread if left untreated. Although it is the least common of skin cancers, it is the most deadly.

Tests are used to screen for different types of cancer when a person does not have symptoms.

Scientists study screening tests to find those with the fewest harms and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) helps a person live longer or decreases a person's chance of dying from the disease. For some types of cancer, the chance of recovery is better if the disease is found and treated at an early stage.

Having a skin exam to screen for skin cancer has not been shown to decrease your chance of dying from skin cancer.

During a skin exam a doctor or nurse checks the skin for moles, birthmarks, or other pigmented areas that look abnormal in color, size, shape, or texture. Skin exams to screen for skin cancer have not been shown to decrease the number of deaths from the disease.

Regular skin checks by a doctor are important for people who have already had skin cancer. If you are checking your skin and find a worrisome change, you should report it to your doctor.

If an area on the skin looks abnormal, a biopsy is usually done. The doctor will remove as much of the suspicious tissue as possible with a local excision. A pathologist then looks at the tissue under a microscope to check for cancer cells. Because it is sometimes difficult to tell if a skin growth is benign (not cancer) or malignant (cancer), you may want to have the biopsy sample checked by a second pathologist.

Most melanomas in the skin can be seen by the naked eye. Usually, melanoma grows for a long time under the top layer of skin (the epidermis) but does not grow into the deeper layer of skin (the dermis). This allows time for skin cancer to be found early. Melanoma is easier to cure if it is found before it spreads.