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.
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:
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.
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.
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.
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.