Melanoma is skin cancer that starts in the cells that make up the outer layer of the skin. It often develops in sun-exposed areas of the body, but can also appear on parts of the skin that have not been exposed to the sun.
Surgery to remove the melanoma and some normal-looking skin around it (a margin of safety) is the main treatment. Your doctor may also suggest chemotherapy.
Symptoms
A sore that won’t heal, a new spot or changes in an existing mole are signs you should see a doctor. You should also talk to your doctor if you have any other concerns, such as itching or bleeding. If you notice a change in any of your skin, look for the ABCDE rule: Asymmetry — the shape of one half of the growth doesn’t match the other; Borders — ragged, notched or uneven; Color – shades of tan, brown or black; Diameter — larger than 1/4 inch (6 millimeters); Evolving — it grows or changes in other ways over time.
If a suspicious area is suspected, the doctor may perform a biopsy by removing some of the tumour under local anaesthetic, sending it to a laboratory for testing. The test results will determine if it is melanoma and, if so, what stage it is at and what kind of treatment you need.
If melanoma is caught early, it’s very treatable. But if the cancer spreads, it can be harder to cure and is often fatal. That’s why it’s important to watch your skin and moles for any changes and visit your doctor for a professional skin exam – at least once a year, more frequently if you have a higher risk of developing skin cancer. Seek the care of a dermatologist who specialises in melanoma and other types of skin cancer.
Diagnosis
For melanoma, doctors examine the skin and carefully check any spots that look different. If they think a spot is suspicious, they might remove it and send it away to be tested (biopsy).
Some melanomas have certain genetic changes that make them more likely to spread or recur. There are gene tests, such as DecisionDx-Melanoma, that can tell if your melanoma is likely to spread or return and help guide treatment. These tests are not yet widely available, but may be an option if your doctor recommends surgery or other treatments.
Your doctor will also consider the size and shape of the tumor and how far it has spread. They might use a handheld magnifying tool and check the area using a system called ABCDE to decide whether it is melanoma. They will also look at the edges of the tumor – normal moles have smooth, straight borders, while melanoma edges might be blurred or jagged and contain different shades of brown or pink.
If a melanoma has spread, your doctor might also test nearby lymph nodes (sentinel lymph node biopsy). They will do this by injecting a substance that outlines the location of lymph vessels in the area. A surgeon will then remove 1 or more sentinel lymph nodes to check for melanoma cells. These are called satellite tumors if they are found near the primary cancer and in-transit metastases if they are found in lymph nodes that are farther away from the primary melanoma.
Treatment
In most cases of melanoma, treatment involves surgery. Sometimes, radiation and chemotherapy are also used. Your doctor will advise you about what type of treatment is best for you based on the size and location of your melanoma, whether it has spread, and your general health.
The first step in deciding your treatment is finding out how far your melanoma has spread. This is called staging. To stage your melanoma, doctors will take a biopsy and perform staging scans. They will also check the lymph nodes around the melanoma. If a lymph node has a very small number of cancer cells, it may not need to be removed. If the melanoma is bigger or has spread, it is more important to remove the lymph node.
If a melanoma has spread, it is often necessary to have further treatments such as surgery, chemotherapy, and radiation therapy. If the melanoma is unresectable, doctors will usually recommend a chemotherapy drug such as dacarbazine (DTIC), or Temodar (temozolomide).
Other types of targeted therapies are now being used to treat some patients with metastatic melanoma. These drugs, such as larotrectinib (Vitrakvi) and entrectinib (Rozlytrek), target a specific genetic change, known as an NTRK fusion, found in many melanoma cells. The benefit of these drugs is that they do not affect healthy cells, so they reduce the side effects of standard chemotherapy.
Prevention
The skin is the largest organ of the human body. It covers a person’s bones, muscles and internal organs and acts as a barrier against injury, infection and extremes of temperature. The outer layer is the epidermis, and beneath that is a thicker, fatty tissue called the hypodermis.
Melanoma usually occurs in sun-exposed areas of the body, especially the legs and arms. It is less common in the head, neck and torso. But it can develop anywhere on the body, even in parts that never see the sun.
Risk factors for melanoma include:
A history of previous melanoma or other skin cancer. A weakened immune system (from illness or certain medications). A condition called xeroderma pigmentosum, which increases a person’s chance of developing cancerous moles on sun-exposed parts of the body.
Some people are at higher risk for melanoma because of their race or ethnicity, the number and size of their moles, or their tendency to burn or freckle. But many people without any known risk factors also get melanoma. This suggests that other things increase a person’s chance of getting the disease, such as a certain gene mutation or a change in the way the immune system works. The best way to reduce your chance of getting melanoma is to practice good sun protection and go to the doctor regularly for a full skin examination.