Skin cancer is a cancer that forms in the tissues of the skin. There are many types of skin cancer. Skin cancer that forms in melanocytes (skin cells that make pigment) is called melanoma. Skin cancer that forms in the lower part of the epidermis (the outer layer of the skin) is called basal cell carcinoma. Skin cancer that forms in squamous cells (flat cells that form the surface of the skin) is called squamous cell carcinoma. Skin cancer that forms in neuroendocrine cells (cells that release hormones in response to signals from the nervous system) is called neuroendocrine carcinoma of the skin. Most skin cancers form in older people on parts of the body exposed to the sun or in people who have weakened immune systems.
Skin cancer is the most common type of cancer in the United States. Each year, more than 68,000 Americans are diagnosed with melanoma, and another 48,000 are diagnosed with an early form of the disease that involves only the top layer of skin. Also, more than 2 million people are treated for basal cell or squamous cell skin cancer each year. Basal cell skin cancer is several times more common than squamous cell skin cancer.
Your skin protects your body from heat, injury, and infection. It also protects your body from damage caused by ultraviolet (UV) radiation (such as from the sun or sunlamps). Your skin stores water and fat. It helps control body heat. Also, your skin makes vitamin D. There are two main layers of the skin:
- Epidermis: The epidermis is the top layer of your skin. It’s mostly made of flat cells called squamous cells. Below the squamous cells deeper in the epidermis are round cells called basal cells. Cells called melanocytes are scattered among the basal cells. They are in the deepest part of the epidermis. Melanocytes make the pigment (color) found in skin. When skin is exposed to UV radiation, melanocytes make more pigment, causing the skin to darken, or tan.
- Dermis: The dermis is the layer under the epidermis. The dermis contains many types of cells and structures, such as blood vessels, lymph vessels, and glands. Some of these glands make sweat, which helps cool your body. Other glands make sebum. Sebum is an oily substance that helps keep your skin from drying out. Sweat and sebum reach the surface of your skin through tiny openings called pores.
Cancer begins in cells, that make up tissues. Tissues make up the skin and other organs of the body. Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they usually die, and new cells take their place. But sometimes this process goes wrong. New cells form when the body doesn’t need them, and old or damaged cells don’t die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor. Growths on the skin can be benign (not cancer) or malignant (cancer). Benign growths are not as harmful as malignant growths.
Benign growths (such as moles):
- Are rarely a threat to life
- Generally can be removed and usually don’t grow back
- Don’t invade the tissues around them
- Don’t spread to other parts of the body
Malignant growths (such as melanoma, basal cell cancer, or squamous cell cancer):
- May be a threat to life
- Often can be removed but sometimes grow back
- May invade and damage nearby organs and tissues
- May spread to other parts of the body
- Types of Skin Cancer
Skin cancers are named for the type of cells that become malignant (cancer). The three most common types are:
- Melanoma: Melanoma begins in melanocytes (pigment cells). Most melanocytes are in the skin. See the picture of a melanocyte and other skin cells.Melanoma can occur on any skin surface. In men, it’s often found on the skin on the head, on the neck, or between the shoulders and the hips. In women, it’s often found on the skin on the lower legs or between the shoulders and the hips. Melanoma is rare in people with dark skin. When it does develop in people with dark skin, it’s usually found under the fingernails, under the toenails, on the palms of the hands, or on the soles of the feet.
- Basal cell skin cancer: Basal cell skin cancer begins in the basal cell layer of the skin. It usually occurs in places that have been in the sun. For example, the face is the most common place to find basal cell skin cancer. In people with fair skin, basal cell skin cancer is the most common type of skin cancer.
- Squamous cell skin cancer: Squamous cell skin cancer begins in squamous cells. In people with dark skin, squamous cell skin cancer is the most common type of skin cancer, and it’s usually found in places that are not in the sun, such as the legs or feet. However, in people with fair skin, squamous cell skin cancer usually occurs on parts of the skin that have been in the sun, such as the head, face, ears, and neck.
Unlike moles, skin cancer can invade the normal tissue nearby. Also, skin cancer can spread throughout the body. Melanoma is more likely than other skin cancers to spread to other parts of the body. Squamous cell skin cancer sometimes spreads to other parts of the body, but basal cell skin cancer rarely does.
When skin cancer cells do spread, they break away from the original growth and enter blood vessels or lymph vessels. The cancer cells may be found in nearby lymph nodes. The cancer cells can also spread to other tissues and attach there to form new tumors that may damage those tissues. The spread of cancer is called metastasis.
When you’re told that you have skin cancer, it’s natural to wonder what may have caused the disease. The main risk factor for skin cancer is exposure to sunlight (UV radiation), but there are also other risk factors. A risk factor is something that may increase the chance of getting a disease. People with certain risk factors are more likely than others to develop skin cancer. Some risk factors vary for the different types of skin cancer.
Risks for Any Type of Skin Cancer
Studies have shown that the following are risk factors for the three most common types of skin cancer:
- Sunlight: a source of UV radiation. It’s the most important risk factor for any type of skin cancer. The sun’s rays cause skin damage that can lead to cancer. Sunlight can be reflected by sand, water, snow, ice, and pavement. The sun’s rays can get through clouds, windshields, windows, and light clothing. In the United States, skin cancer is more common where the sun is strong. For example, more people in Texas than Minnesota get skin cancer. Also, the sun is stronger at higher elevations, such as in the mountains. Doctors encourage people to limit their exposure to sunlight.
- Severe, blistering sunburns: People who have had at least one severe, blistering sunburn are at increased risk of skin cancer. Although people who burn easily are more likely to have had sunburns as a child, sunburns during adulthood also increase the risk of skin cancer.
- Lifetime sun exposure: The total amount of sun exposure over a lifetime is a risk factor for skin cancer.
- Tanning: Although a tan slightly lowers the risk of sunburn, even people who tan well without sun burning have a higher risk of skin cancer because of more lifetime sun exposure.
- Sunlamps and tanning booths: Artificial sources of UV radiation, such as sunlamps and tanning booths, can cause skin damage and skin cancer. We encourage people, especially young people, to avoid using sunlamps and tanning booths. The risk of skin cancer is greatly increased by using sunlamps and tanning booths before age 30.
- Personal history: People who have had melanoma have an increased risk of developing other melanomas. Also, people who have had basal cell or squamous cell skin cancer have an increased risk of developing another skin cancer of any type.
- Family history: Melanoma sometimes runs in families. Having two or more close relatives (mother, father, sister, brother, or child) who have had this disease is a risk factor for developing melanoma. Other types of skin cancer also sometimes run in families.
- Skin that burns easily: Having fair (pale) skin that burns in the sun easily, blue or gray eyes, red or blond hair, or many freckles increases the risk of skin cancer.
- Certain medical conditions or medicines: Medical conditions or medicines (such as some antibiotics, hormones, or antidepressants) that make your skin more sensitive to the sun increase the risk of skin cancer. Also, medical conditions or medicines that suppress the immune system increase the risk of skin cancer.
Other Risk Factors for Melanoma
The following risk factors increase the risk of melanoma:
- Dysplastic nevus: A dysplastic nevus is a type of mole that looks different from a common mole. A dysplastic nevus may be bigger than a common mole, and its color, surface, and border may be different. It’s usually wider than a pea and may be longer than a peanut. A dysplastic nevus can have a mixture of several colors, from pink to dark brown. Usually, it’s flat with a smooth, slightly scaly or pebbly surface, and it has an irregular edge that may fade into the surrounding skin. A dysplastic nevus is more likely than a common mole to turn into cancer. However, most do not change into melanoma. A doctor will remove a dysplastic nevus if it looks like it might have changed into melanoma.
- More than 50 common moles: Usually, a common mole is smaller than a pea, has an even color (pink, tan, or brown), and is round or oval with a smooth surface. Having many common moles increases the risk of developing melanoma.
Other Risk Factors for Both Basal Cell and Squamous Cell Skin Cancers
The following risk factors increase the risk of basal cell and squamous cell skin cancers:
- Old scars, burns, ulcers, or areas of inflammation on the skin
- Exposure to arsenic at work
- Radiation therapy
Other Risk Factors for Squamous Cell Cancer
The risk of squamous cell skin cancer is increased by the following:
- Actinic keratosis: Actinic keratosis is a type of flat, scaly growth on the skin. It is most often found on areas exposed to the sun, especially the face and the backs of the hands. The growth may appear as a rough red or brown patch on the skin. It may also appear as cracking or peeling of the lower lip that does not heal. Without treatment, this scaly growth may turn into squamous cell skin cancer.
- HPV (human papillomavirus): Certain types of HPV can infect the skin and may increase the risk of squamous cell skin cancer. These HPVs are different from the HPV types that cause cervical cancer and other cancers in the female and male genital areas.
Symptoms of Melanoma
Often the first sign of melanoma is a change in the shape, color, size, or feel of an existing mole. Melanoma may also appear as a new mole. Thinking of “ABCDE” can help you remember what to look for:
- 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 pigment 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 the size of a pea (larger than 6 millimeters or about 1/4 inch).
- Evolving: The mole has changed over the past few weeks or months.
Melanomas can vary greatly in how they look. Many show all of the ABCDE features. However, some may show changes or abnormal areas in only one or two of the ABCDE features.
In more advanced melanoma, the texture of the mole may change. The skin on the surface may break down and look scraped. It may become hard or lumpy. The surface may ooze or bleed. Sometimes the melanoma is itchy, tender, or painful.
Symptoms of Basal Cell and Squamous Cell Skin Cancers
A change on the skin is the most common sign of skin cancer. This may be a new growth, a sore that doesn’t heal, or a change in an old growth. Not all skin cancers look the same. Usually, skin cancer is not painful.
If you have a change on your skin, your doctor must find out whether or not the problem is from cancer. You may need to see a dermatologist, a doctor who has special training in the diagnosis and treatment of skin problems. Your doctor will check the skin all over your body to see if other unusual growths are present.
If your doctor suspects that a spot on the skin is cancer, you may need a biopsy. For a biopsy, your doctor may remove all or part of the skin that does not look normal. The sample goes to a lab. A pathologist checks the sample under a microscope. Sometimes it’s helpful for more than one pathologist to check the tissue for cancer cells. You may have the biopsy in a doctor’s office or as an outpatient in a clinic or hospital. You’ll probably have local anesthesia.
There are four common types of skin biopsies:
- Shave biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth.
- Punch biopsy: The doctor uses a sharp, hollow tool to remove a circle of tissue from the abnormal area.
- Incisional biopsy: The doctor uses a scalpel to remove part of the growth.
- Excisional biopsy: The doctor uses a scalpel to remove the entire growth and some tissue around it. This type of biopsy is most commonly used for growths that appear to be melanoma.
If the biopsy shows that you have skin cancer, we need to find out the stage (extent) of the disease to help you choose the best cancer treatment.
The stage is based on:
- The size (width) of the growth
- How deeply it has grown beneath the top layer of skin
- Whether cancer cells have spread to nearby lymph nodes or to other parts of the body
When skin cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary (original) tumor. For example, if skin cancer spreads to the lung, the cancer cells in the lung are actually skin cancer cells. The disease is metastatic skin cancer, not lung cancer. For that reason, it’s treated as skin cancer, not as lung cancer. Doctors sometimes call the new tumor “distant” disease.
Blood tests and an imaging test such as a chest x-ray, a CT scan, an MRI, or a PET scan may be used to check for the spread of skin cancer. For example, if a melanoma growth is thick, the doctor may order blood tests and an imaging test.
For squamous cell skin cancer or melanoma, the doctor will also check the lymph nodes near the cancer on the skin. If one or more lymph nodes near the skin cancer are enlarged (or if the lymph node looks enlarged on an imaging test), your doctor may use a thin needle to remove a sample of cells from the lymph node (fine-needle aspiration biopsy). A pathologist will check the sample for cancer cells.
Even if the nearby lymph nodes are not enlarged, the nodes may contain cancer cells. The stage is sometimes not known until after surgery to remove the growth and one or more nearby lymph nodes. For thick melanoma, surgeons may use a method called sentinel lymph node biopsy to remove the lymph node most likely to have cancer cells. Cancer cells may appear first in the sentinel node before spreading to other lymph nodes and other places in the body.
Stages of Melanoma
These are the stages of melanoma:
- Stage 0: The melanoma involves only the top layer of skin. It is called melanoma in situ.
- Stage I: The tumor is no more than 1 millimeter thick (about the width of the tip of a sharpened pencil.) The surface may appear broken down. Or, the tumor is between 1 and 2 millimeters thick, and the surface is not broken down.
- Stage II: The tumor is between 1 and 2 millimeters thick, and the surface appears broken down. Or, the thickness of the tumor is more than 2 millimeters, and the surface may appear broken down.
- Stage III: The melanoma cells have spread to at least one nearby lymph node. Or, the melanoma cells have spread from the original tumor to tissues nearby.
- Stage IV: Cancer cells have spread to the lung or other organs, skin areas, or lymph nodes far away from the original growth. Melanoma commonly spreads to other parts of the skin, tissue under the skin, lymph nodes, and lungs. It can also spread to the liver, brain, bones, and other organs.
Stages of Other Skin Cancers
These are the stages of basal cell and squamous cell skin cancers:
- Stage 0: The cancer involves only the top layer of skin. It is called carcinoma in situ.
Bowen disease is an early form of squamous cell skin cancer. It usually looks like a reddish, scaly or thickened patch on the skin. If not treated, the cancer may grow deeper into the skin.
- Stage I: The growth is as large as 2 centimeters wide (more than three-quarters of an inch or about the size of a peanut).
- Stage II: The growth is larger than 2 centimeters wide.
- Stage III: The cancer has invaded below the skin to cartilage, muscle, or bone. Or, cancer cells have spread to nearby lymph nodes. Cancer cells have not spread to other places in the body.
- Stage IV: The cancer has spread to other places in the body. Basal cell cancer rarely spreads to other parts of the body, but squamous cell cancer sometimes spreads to lymph nodes and other organs.
Treatment for skin cancer depends on the type and stage of the disease, the size and place of the tumor, and your general health and medical history. In most cases, the goal of treatment is to remove or destroy the cancer completely. Most skin cancers can be cured if found and treated early. Skin cancer treatments may include:
- Photodynamic Therapy
- Biological Therapy
- Radiation Therapy
Sometimes all of the skin cancer is removed during the biopsy. In such cases, no more treatment is needed. If you do need more treatment, our doctor can describe your treatment choices and what to expect. You and our doctors can work together to develop a cancer treatment plan that meets your needs.
Surgery is the usual treatment for people with skin cancer. In some cases, our doctor may suggest chemotherapy, photodynamic therapy, or radiation therapy. People with melanoma may also have biological therapy.
People with advanced skin cancer may need to see one of our medical oncologists or radiation oncologists. Your health care team may also include an oncology nurse, a social worker, and a registered dietitian.
Because skin cancer treatment may damage healthy cells and tissues, unwanted side effects sometimes occur. Side effects depend mainly on the type and extent of the treatment. Side effects may not be the same for each person. Before treatment starts, your health care team will tell you about possible side effects and suggest ways to help you manage them.
Many skin cancers can be removed quickly and easily. But some people may need supportive care to control pain and other symptoms, to relieve the side effects of treatment, and to help them cope with the feelings that a diagnosis of cancer can bring. Please feel free to contact Choice Cancer Care for additional information and treatment options.
After treatment for skin cancer, you’ll need regular checkups (such as every 3 to 6 months for the first year or two). Your doctor will monitor your recovery and check for any new skin cancers. Regular checkups help ensure that any changes in your health are noted and treated if needed.
During a checkup, you’ll have a physical exam. People with melanoma may have x-rays, blood tests, and scans of the chest, liver, bones, and brain.
People who have had melanoma have an increased risk of developing a new melanoma, and people with basal or squamous cell skin cancers have a risk of developing another skin cancer of any type. It’s a good idea to get in a routine for checking your skin for new growths or other changes. Keep in mind that changes are not a sure sign of skin cancer. Still, you should tell your doctor about any changes right away.
Follow your doctor’s advice about how to reduce your risk of developing skin cancer again.
People with skin cancer are at risk of developing another skin cancer. Limit your time in the sun and stay away from sunlamps and tanning booths. Keep in mind that getting a tan may increase your risk of developing another skin cancer.
The best way to prevent skin cancer is to protect yourself from the sun:
- Avoid outdoor activities during the middle of the day. The sun’s rays are the strongest between 10 a.m. and 4 p.m. When you must be outdoors, seek shade when you can.
- Protect yourself from the sun’s rays reflected by sand, water, snow, ice, and pavement. The sun’s rays can go through light clothing, windshields, windows, and clouds.
- Wear long sleeves and long pants. Tightly woven fabrics are best.
- Wear a hat with a wide brim all around that shades your face, neck, and ears. Keep in mind that baseball caps and some sun visors protect only parts of your skin.
- Wear sunglasses that absorb UV radiation to protect the skin around your eyes.
- Use sunscreen lotions with a sun protection factor (SPF) of at least 15. (Some doctors will suggest using a lotion with an SPF of at least 30.) Apply the product’s recommended amount to uncovered skin 30 minutes before going outside, and apply again every two hours or after swimming or sweating.
Sunscreen lotions may help prevent some skin cancers. It’s important to use a broad-spectrum sunscreen lotion that filters both UVB and UVA radiation. But you still need to avoid the sun during the middle of the day and wear clothing to protect your skin.
Source of information: National Cancer Institute – www.cancer.gov