Skin cancer is the most common type of cancer in the United States. According to current estimates, 40 to 50 percent of Americans who live to age 65 will have skin cancer at least once. Melanoma is the most serious of the skin cancers, and the number of people who develop melanoma is increasing at a faster rate than that of any other cancer.
The skin is the body's outer covering which protects us from heat, light, injury and infection. It regulates body temperature, and stores water, fat and vitamin D. It is the body's largest organ. It is made up of two layers called the epidermis and the dermis. The epidermis is the outer layer of the skin and it is mostly of flat, scale-like cells called squamous cells. Under the squamous cells are round cells called basal cells The deepest part of the epidermis contains melanocytes which are cells that produce a pigment called melanin which gives the skin its color.
When skin is exposed to the sun, the melanocytes produce more pigment causing the skin to tan or darken. Clusters of melanocytes and surrounding tissue form common noncancerous growths called moles.
The dermis is the inner layer of the skin, which contains blood and lymph vessels, hair follicles and glands that produce sweat (to regulate body temperature), and sebum (an oily substance that helps keep the skin from drying out). Sweat and sebum reach the skin's surface through tiny openings called pores.
What is Skin Cancer?
Cancer is a group of many related diseases that begin in cells, the body's basic unit of life. The body is made up of many types of cells, and normally, cells grow and divide to produce more cells only when the body needs them. Sometimes, however, cells keep dividing when new cells are not needed. These extra cells form a mass of tissue, called a growth or tumor. There are two types, benign and malignant.
Benign tumors are not cancer. They can usually be removed by surgery, and in most cases, they do not come back. Cells from benign tumors do not spread to other parts of the body and are not a threat to life.
Malignant tumors are cancer. They can invade and destroy nearby healthy tissues and organs. Cancer cells also can spread, or metastasize, to other parts of the body and form new tumors.
Two common kinds of skin cancer are basal cell carcinoma and squamous cell carcinoma (also called nonmelanoma skin cancer). Carcinoma is cancer that begins in the cells that cover or line an organ. Melanoma is a malignancy of the melanocytes and is the most serious form of skin cancer.
Basal cell carcinoma is a slow-growing cancer that seldom spreads to other parts of the body.
Squamous cell carcinoma also rarely spreads, but it does so more often than basal cell carcinoma. It is important that skin cancers be found and treated early because they can invade and destroy nearby tissue.
Melanoma occurs when melanocytes become malignant. When melanoma starts in the skin (it may also start in other parts of the body such as the eye) the disease is called cutaneous melanoma. When melanoma spreads (metastasizes), cancer cells are also found in the lymph nodes, and it may mean that the cancer has also spread to other parts of the body such as the liver, lungs or brain. The cancer cells of the new tumor are still melanoma cells, and the disease is called metastatic melanoma rather than liver, lung or brain cancer.
What causes Skin Cancer?
Although anyone can get skin cancer, the risk is greatest for people who have fair skin that freckles easily, and often those with red or blond hair and blue or light-colored eyes.
Ultraviolet (UV) Radiation from the sun is the main cause of skin cancer. Artificial sources of UV radiation, such as sunlamps and tanning booths, can also cause skin cancer. The risk of developing skin cancer is affected by where a person lives.
People who live in areas that get high levels of UV radiation from the sun are more likely to get skin cancer. In the United States, for example, skin cancer is more common in Texas than it is in Minnesota, where the sun is not as strong.
Worldwide, the highest rates of skin cancer are found in areas that receive high amounts of UV radiation such as South Africa, Australia and New Zealand.
The risk of developing skin cancer is related to lifetime exposure to UV radiation. Most skin cancers appear after age 50, but the sun's damaging effects begin at an early age. Therefore, protection should start in childhood to prevent skin cancer later in life.
Whenever possible, people should avoid exposure to the midday sun (from 10 a.m. to 2 p.m. standard time, or from 11 a.m. to 3 p.m. daylight saving time). Protective clothing, such as sun hats and long sleeves, can block out the sun's harmful rays. Sunscreens with a sun protection factor (SPF) of 15 to 30 or higher block most of the sun's harmful rays.
What are the risk factors for Melanoma?
Family history of melanoma -- Having two or more close relatives who have had this disease is a risk factor because melanoma sometimes runs in families
Dysplastic nevi -- Dysplastic nevi are a certain type of mole, more likely than ordinary moles to become cancerous. The risk of melanoma is greater for people with a large number of dysplastic nevi.
History of melanoma -- People who have been treated for melanoma are at a high risk for developing a second melanoma.
Weakened immune system -- People whose immune system is weakened by certain cancers, by drugs given following organ transplants, or by AIDS are at increased risk of developing melanoma.
Large numbers of ordinary moles (more than 50) -- Because melanoma usually begins in the melanocytes of an existing mole, having many moles increases the risk of developing this disease.
Exposure to Ultraviolet (UV) radiation -- UV radiation from the sun causes premature aging of the skin and skin damage that can lead to melanoma. Artificial sources of UV radiation, such as sunlamps and tanning booths, also can cause skin damage and probably an increased risk of melanoma.
Severe, blistering sunburns -- People who have had one or more severe, blistering sunburns as a child or teenager are at increased risk for melanoma. Sunburns in adulthood are also a risk factor for melanoma.
Fair skin -- Melanoma occurs more frequently in people who have fair skin that burns or freckles easily (these people also usually have red or blond hair and blue eyes).
People who are concerned about melanoma should talk with their doctors about the disease, the symptoms to watch for, and an appropriate schedule for checkups. The doctor's advice will be based on the person's personal and family history, medical history, and the other risk factors described above.
Symptoms of Skin Cancer
Basal and Squamous cell cancers are found mainly on areas of the skin that are exposed to the sun such as the head, face, neck, hands, and arms however, skin cancer can occur anywhere. The most common warning sign of skin cancer is a change on the skin, especially a new growth or a sore that doesn't heal. Skin cancers don't all look the same. For example, the cancer may start as a small, smooth, shiny, pale, or waxy lump. Or it can appear as a firm red lump. Sometimes, the lump bleeds or develops a crust. Skin cancer can also start as a flat, red spot that is rough, dry, or scaly.
Symptoms of Melanoma
Melanomas are usually first noticed because of a change in the size, shape, color or feel of an existing mole. Other frequent findings are newly formed fine scales or itching in a mole. Thinking of "ABCD" can help you remember what to watch for:
- Asymmetry -- the shape of one half does not match the other.
- Border -- The edges are often ragged, notched, blurred, or irregular in outline; the pigment may spread into the surrounding skin.
- Color - -The color is uneven. Shades of black, brown, and tan may be present. Areas of white, gray, red, pink, or blue also may be seen.
- Diameter -- There is a change in size, usually an increase. Melanomas are usually larger than the eraser of a pencil (5 mm or 1/4 inch).
Melanomas can vary greatly in the ways they look. Many show all of the ABCD features but some may show changes or abnormalities in only one or two of the ABCD features.
Melanoma can be cured if it is diagnosed and treated when the tumor is thin and has not deeply invaded the skin. However, if a melanoma is not removed at its early stages, cancer cells may grow downward from the skin surface, invading healthy tissue. When a melanoma becomes thick and deep, the disease often spreads to other parts of the body and is difficult to control.
Changes in the skin are not sure signs of cancer; however, it is important to see a doctor if any symptom lasts longer than 2 weeks. Don't wait for the area to hurt -- skin cancers seldom cause pain.
Detection of Skin Cancer
The cure rate for skin cancer is very high if detected early. It is important to examine the skin regularly to check for new growths or other changes in the skin. Any new, colored growths or any changes in growths that are already present should be reported to a doctor without delay
Doctors should also check the skin during routine physical exams. People who have already had skin cancer should be sure to have regular exams so that the doctor can check the treated are of skin and other areas cancer may develop.
How To Do a Skin Self-Exam
The best time to do a skin self-exam is after a shower or bath. The skin should be checked in a well-lit room using a full-length mirror and a hand-held mirror. It's best to begin by learning where birthmarks, moles, and blemishes are and what they usually look and feel like. Check for anything new, especially a change in the size, shape, texture, or color of a mole or a sore that does not heal.
Check yourself from head to toe. Don't forget to check all areas of the skin, including the back, the scalp, between the buttocks, and the genital area:
- Look at the front and back of your body in the mirror, then raise your arms and look at your left and right sides.
- Bend your elbows and look carefully at your fingernails, palms, forearms (including the undersides), and upper arms.
- Examine the back, front, and sides of your legs. Also look between the buttocks and around the genital area.
- Sit and closely examine your feet, including the toenails, the soles, and the spaces between the toes.
- Look at your face, neck, ears, and scalp. You may want to use a comb or a blow dryer to move hair so that you can see better. You also may want to have a relative or friend check through your hair because this is difficult to do yourself.
By checking your skin regularly, you will become familiar with what is normal for you. It may be helpful to record the dates of your skin exams and to write notes about the way your skin looks. If you find anything unusual, see your doctor right away.
Diagnosis of Skin Cancer
Basal cell carcinoma and squamous cell carcinoma are generally diagnosed and treated in the same way. When an area of skin does not look normal, the doctor may remove all or part of the growth. This is procedure is called a biopsy. The tissue is examined to check for cancer cells
Doctors generally divide skin cancer into two stages: local (affecting only the skin) or metastatic (spreading beyond the skin). Because basal cell carcinomas and squamous cell carcinomas rarely spread beyond the skin, a biopsy often is the only test needed to determine the stage.
In cases where the growth is very large or has been present for a long time, the doctor will carefully check the lymph nodes in the area, and additional tests, such as special x-rays, will be used to find out whether the cancer has spread to other parts of the body. Knowing the stage of a skin cancer helps determine the treatment plan.
Diagnosis of Melanoma
A biopsy is also the only way to make a definite diagnosis of melanoma. Usually, attempts are made to remove the entire growth. If the growth is too large to be removed entirely, a sample of tissue will be taken.
If melanoma is found, various tests and procedures will be conducted to determine the extent or stage of the disease. Removal of nearby lymph nodes is sometimes necessary. The treatment plan is dependent of the location and thickness of the tumor, how deep and whether it has metastasized.
Treatment of Skin Cancer
The main objective of treating skin cancer is to remove or destroy the cancer completely with as small a scar as possible.
Treatment of skin cancer usually involves some type of surgery. In some cases, treatment will involve radiation therapy, chemotherapy or a combination of both.
Surgery -- Many skin cancers can be cut from the skin quickly and easily. In fact, the cancer is sometimes completely removed at the time of the biopsy, and no further treatment is needed.
Curettage and Electrodesiccation involves numbing the area with a local anesthetic and scooping the skin cancer out with a sharp spoon shaped instrument called a curette. The area is then treated with an electric current from a special machine (a procedure called electrodesiccation) to control bleeding and kill any cancer cells remaining around the edge of the wound. Most patients develop a flat white scar.
Moh's Surgery is a special type of surgery performed by specialists. The aim is to remove all of the cancerous tissue and as little of the healthy tissue as possible, and is particularly useful when the shape and depth of the tumor is unknown. This method is also used to remove large tumors, those in hard-to-treat places, and cancers that have recurred. The procedure is performed under local anesthetic, and the cancer is shaved off one thin layer at a time. Each layer is checked under a microscope until the entire tumor is removed. The degree of scarring depends on the location and size of the treated area.
Cryosurgery is the use of extreme cold to freeze and kill the abnormal cells. Liquid nitrogen is used to treat precancerous skin conditions such as actinic keratosis, and certain small skin cancers. After the area is thawed, the dead tissue falls off. More than one treatment may be necessary to remove the growth completely. Pain and swelling may be present after the area thaws, and a white scar may form in the treated area.
Laser Therapy uses a narrow beam of light to remove or destroy cancer cells. This procedure is sometimes used for cancers that only involve the outer layer of skin.
Skin Grafts are often needed to close the wound and reduce the amount of scarring, especially if a large cancer is removed. The procedure involves taking a piece of healthy skin from another part of the body to replace the skin that was removed.
Radiation Therapy (radiotherapy) uses high-energy rays to damage cancer cells and stop them from growing. This treatment is often used for cancers in areas that are difficult to treat with surgery (example eyelid, the tip of the nose, or the ear). Several treatments may be necessary. Radiation therapy may cause a rash or make the skin in the area dry or red. Changes in skin color or texture may develop after the treatment, and may become more noticeable many years later.
Topical Chemotherapy is the use of anticancer drug in a cream or lotion applied to the skin. Fluorouracil (also called 5-FU) is used to treat precancerous conditions such as actinic keratosis and cancers limited to the top layer of skin. Intense inflammation is common during treatment, but scars usually do not occur.
Treatment of Melanoma and Side Effects
Surgery -- The standard treatment for melanoma is removal (excision). It is necessary to remove not only the tumor but also some normal tissue around it in order to minimize the chance that any cancer will be left in the area. The amount of healthy tissue removed depends on the thickness of the melanoma and how deeply it has invaded the skin. In cases where the melanoma is very thin, enough tissue is often removed during the biopsy, and no further surgery is necessary.
If the melanoma was not completely removed during the biopsy, the remaining tumor is removed. In most cases, additional surgery is performed to remove normal-looking tissue around the tumor (called the margin) to make sure all melanoma cells are removed. This is necessary, even for thin melanomas. For thick melanomas, it may be necessary to do a wider excision to take out a larger margin of tissue. Where large areas of tissue are removed, a skin graft may be performed.
Lymph nodes near the tumor may be also removed during surgery. If cancer cells are found in the lymph nodes, it may mean that the disease has spread to other parts of the body.
Surgery is generally not effective in controlling melanoma that is known to have spread to other parts of the body. In such cases, doctors may use other methods of treatment, such as chemotherapy, biological therapy, radiation therapy, or a combination of these methods. When therapy is given after surgery (primary therapy) to remove all cancerous tissue, the treatment is called adjuvant therapy. The goal of adjuvant therapy is to kill any undetected cancer cells that may remain in the body.
The side effects of surgery depend mainly on the size and location of the tumor and the extent of the operation. Pain and discomfort after surgery can be controlled with pain relieving medicine. It is also common for patients to feel tired or weak for a while. The length of time it takes to recover from an operation varies for each patient. Scarring may also be a concern for some patients.
Chemotherapy is the use of one or more drugs to kill cancer cells. It is generally a systemic therapy, meaning that it can affect cancer cells throughout the body. Anticancer drugs are given by mouth or by injection into a blood vessel. Chemotherapy is usually given in cycles: a treatment period followed by a recovery period, then another treatment period, and so on.
Side effects depend largely on the specific drugs and the dose (amount of drug given). Common side effects of chemotherapy include nausea and vomiting, hair loss, mouth sores, and fatigue.
Biological therapy (immunotherapy) is a form of treatment that uses the body's immune system, either directly or indirectly, to fight cancer or to lessen side effects caused by some cancer treatments. Biological therapy is also a systemic therapy and involves the use of substances called biological response modifiers (BRMs). The body normally produces these substances in small amounts in response to infection and disease.
Using modern laboratory techniques, scientists can produce BRMs in large amounts for use in cancer treatment. In some cases, biological therapy given after surgery can help prevent melanoma from recurring.
For patients with metastatic melanoma or a high risk of recurrence, interferon-alfa and interleukin-2 (also called aldesleukin) may be recommended after surgery.
The side effects caused by biological therapy vary with the type of treatment. These treatments may cause flu-like symptoms, such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Patients may also bleed or bruise easily, get a skin rash, or have swelling. These problems can be severe, but they go away after treatment stops.
Radiation therapy (radiotherapy) is the use of high-energy rays to kill cancer cells. In some cases, radiation therapy is used to relieve some of the symptoms caused by melanoma. Radiation therapy is a local therapy, as it affects cells only in the treated area. Radiation therapy is most commonly used to help control melanoma that has spread to the brain, bones, and other parts of the body.
Side effects of radiation therapy depend mainly on the part of the body that is treated and the treatment dose. Common side effects of radiation therapy include fatigue and hair loss in the treated area.
Developments in Treatment of Skin Cancer
There are a number of new treatments in development for the treatment of skin cancer. Photodynamic therapy is a treatment that destroys cancer cells with a combination of laser light and drugs that make the cells sensitive to light.
Biological therapy (also called immunotherapy) is a form of treatment to improve the body's natural ability to fight cancer. Interferon and tumor necrosis factor are types of biological therapy under study for skin cancer.
Drugs used in the Treatment of Skin Cancer
Developments in Treatment of Melanoma
One method of giving chemotherapy drugs currently under investigation is called limb perfusion. It is being tested for use when melanoma occurs only on an arm or leg.
In limb perfusion the flow of blood to and from the limb is stopped for a while with a tourniquet. Anticancer drugs are then put into the blood of the limb. The patient receives high doses of drugs directly into the area where the melanoma occurred. Since most of the anticancer drugs remain in one limb, limb perfusion is not truly systemic therapy.
A new procedure for the treatment of melanoma is sentinel lymph node biopsy, which may eventually reduce the number of lymph nodes that need to be removed for biopsy. The procedure involves injecting a blue dye or a small amount of radioactive material near the area where the tumor was. This material flows into the sentinel lymph node(s) (the first lymph node(s) that the cancer is likely to spread to from the primary tumor).
A surgeon then looks for the dye or uses a scanner to find the sentinel lymph node(s) and then removes it for examination by a pathologist. If the sentinel lymph node(s) is positive for cancer cells, then the rest of the surrounding lymph nodes are usually removed; if it is negative, the remaining lymph nodes may not need to be removed.