Melanoma at a glance
- Melanoma is a type of cancer that develops in the melanocyte cells that produce melanin.
- Melanin gives skin its color and protects it from harmful ultraviolet (UV) rays, exposure to which is the main cause of melanoma.
- Melanoma, the rarest form of skin cancer, accounts for only 1 percent of all skin cancers but has a high death rate if undetected.
- People most at risk of getting this cancer have had considerable exposure to UV light, are fair-skinned and have a lot of moles.
- When detected at an early stage, oncologists can frequently cure it.
- Oncologists generally surgically remove melanoma and may also use other treatments such as targeted therapy or chemotherapy.
What is melanoma?
The melanoma form of skin cancer, the most common of all cancers, occurs when melanocyte cells grow out of control, the hallmark of all cancers. Melanocyte cells produce the melanin that gives skin its color and also protect skin from damaging UV light exposure.
Melanoma, also called malignant melanoma or cutaneous melanoma, is the rarest form of skin cancer and the most serious, because it has the greatest risk of spreading to other parts of the body. Oncologists categorize skin cancer according to which of the three types of skin cells it begins in, either melanocytes, basal cells or squamous cells. Basal cell carcinoma and squamous cell carcinoma are non-melanoma skin cancers that rarely spread.
Skin cancers develop when sun exposure or other factors damage the DNA (deoxyribonucleic acid) of skin cells. The damage causes mutations or genetic defects that result in rampant cell growth and the formation of tumors in the melanocytes.
Melanoma can develop anywhere on the body. But it usually starts in places that have been most exposed to the sun or tanning lamps. In men, most cases start on the trunk (the chest or back). In women, most cases begin on the legs. This cancer also commonly occurs on the neck and face.
The greater the exposure to UV rays from the sun or tanning beds, the greater the chance of melanoma. But since the cancer can also appear in areas that aren’t exposed to UV rays (soles of the feet and palms), physicians believe it is also caused by a combination of other factors, including environmental and genetic.
Doctors diagnose this form of skin cancer through examination of moles and biopsies of skin or lymph nodes. They stage the disease, which is determining the extent of the cancer and if it has spread (metastasized), through physical exams, biopsies and other imaging tests such as CT or MRI scans.
Sometimes physicians can’t determine where the original cancer began, since it can spread quickly to lymph nodes, lungs, the brain or other areas.
Risks of melanoma skin cancer
There are a number of risk factors that may or may not increase a person’s chance of getting the disease. Some risk factors can be prevented, some can’t. Risk factors include:
- UV light exposure from sunlight or tanning beds
- Moles, and the more moles, the greater the risk
- Dysplastic nevi are abnormal moles often larger than ordinary moles and have irregular borders and a mix of colors. Not uncommon, they are more likely than ordinary moles to become cancerous.
- Fair skin, light hair and freckles. The lighter the skin, the higher the risk of melanoma, which is 20 times more common in whites than in African-Americans
- History of sunburn, even one severe, blistering sunburn as a child
- Age has a bearing on risk, as more cases occur in older patients, though it also occurs in younger people and sometimes in children
- Gender. Before age 45, the risk of melanoma is higher for women; after age 45, it’s higher for men
- Family history. About 10 percent of those with melanoma have a family history of the disease; if a parent, sibling or child has it, the chances of getting the disease are 50 percent greater
- Personal history. Melanoma returns in about 5 percent of cases; people with basal or squamous cell skin cancer are also at greater risk of getting it
- Weakened immune system, which may result from chemotherapy, an organ transplant or other diseases, increases the risk of having this cancer.
People can reduce their risk by limiting exposure to UV rays, wearing sunscreen and avoiding tanning beds. Those who have a lot of moles should do monthly self-exams to check for changes in the moles and get regular checkups from a dermatologist.
Signs and symptoms of melanoma
Normal moles generally have a distinct border and a uniform color such as tan, brown or black. They’re oval or round and usually smaller than one-quarter inch or about six millimeters in diameter (the size of a pencil eraser).
If a person notices a new spot, unusual looking growth or a mole that is changing in size, shape or color, he or she should see a physician.
Physicians often recommend the ABCDE rule as a guide to spotting signs of this skin cancer. However, all malignant moles will not have all or any of these characteristics. Be sure to check with your physician if you notice any of the following.
- A (asymmetry): The two halves of a mole or birthmark are not the same size and shape
- B (border): Irregular edges or borders that are jagged or indistinct
- C (color): The color varies and may include black or brown shades, as well as areas of red, pink, blue or white resembling patches
- D (diameter): Bigger than six millimeters (one-quarter inch)
- E (evolving): The mole’s color, size or shape changes, or it has started itching, bleeding or becoming painful.
Other signs include: a nonhealing sore; redness or swelling outside the border; an alteration of the mole’s surface (a nodule, bump or scaliness appears, and bleeding and oozing may occur); or pigment spreading into skin surrounding the spot.
Treatment of melanoma skin cancer
Treatments depend on the size and stage of the cancer, as well as such other factors as overall health. The team of doctors making treatment decisions may include a dermatologist, surgical oncologist, medical oncologist or radiation oncologist.
Early-stage melanomas are often treated with surgery alone; more advanced cases may need additional treatments. In addition to the treatments listed below, patients may want to discuss clinical trials options with their oncologist.
- Surgery can sometimes remove the tumor, and dermatologists can remove thin melanomas during a biopsy. The tumor is removed along with a border of normal skin and a layer of tissue beneath it. Lymph nodes may also be removed if the cancer has spread. A surgical cure for this cancer that has metastasized to other organs is unlikely. Surgical risks include infection, anesthesia reactions, blood loss and organ and tissue damage.
- Immunotherapy (or biological therapy) involves medicines to stimulate the immune system to recognize and destroy cancer cells.
- Targeted therapy attacks cancer cells without killing healthy cells and is sometimes an option for patients with specific genetic mutations. Drugs or other substances can identify and attack genes or other agents that allow cancer cells to proliferate. Side effects may occur, such as fatigue and mouth sores.
- Chemotherapy, which involves powerful medicine that travels through the bloodstream to kill cancer cells throughout the body, may be used to relieve symptoms or extend survival for some patients. Side effects vary but can include loss of hair, nausea, diarrhea and fatigue.
- Radiation or X-rays can kill cancer cells. Oncologists don’t usually choose radiation to treat the original melanoma but it may reduce the chances of recurrence after surgery to remove lymph nodes. Radiation also treats recurring melanoma or is administered to relieve symptoms of metastatic melanoma, especially when the cancer has spread to the brain or bones. Radiation may cause side effects such as sore throat and shortness of breath.