Malignant melanoma is a serious form of skin cancer that begins in the cells responsible for producing skin pigment. While it represents only about one percent of all skin cancers, it causes the majority of skin cancer deaths. The encouraging news is that when detected early, melanoma has a cure rate approaching 99 percent, making awareness and early detection absolutely critical.
Understanding the Disease
Malignant melanoma develops from special cells called melanocytes, which produce melanin, the pigment that gives skin its color. These cells are found in the deepest part of the outer skin layer. When something goes wrong with these cells, they can begin growing in an uncontrolled manner, forming melanoma. The disease got its name from the Greek words meaning “black tumor” because most melanomas appear as black or brown spots on the skin. However, some melanomas can be pink, red, purple, or even the same color as the surrounding skin, which can make them harder to recognize.[2]
About thirty percent of melanomas develop from existing moles that people have had for years. The remaining seventy percent appear on what looks like completely normal skin. This makes it especially important to watch your entire skin surface, not just the moles you already know about. The fact that most melanomas arise on skin that previously looked healthy means that everyone needs to be vigilant about changes anywhere on their body.[2][4]
Unlike other skin cancers that tend to stay localized, melanoma has the ability to spread quickly to other parts of the body. It can move through the lymphatic system to lymph nodes or travel through the bloodstream to distant organs such as the liver, lungs, bones, and brain. This spreading ability is what makes melanoma particularly dangerous. Once the cancer spreads beyond the skin, treatment becomes much more challenging and survival rates decrease significantly.[3]
How Common Is Melanoma Worldwide
Melanoma accounts for only about one percent of all skin cancers diagnosed each year, yet it is responsible for the vast majority of deaths from skin cancer. The disease has become increasingly common over recent decades. The number of new melanoma cases has increased dramatically over the past thirty years, with many experts pointing to rising levels of ultraviolet radiation exposure as a primary driver of this troubling trend.[2][14]
Between 2014 and 2018, the rate of metastatic melanoma in the United States was estimated at approximately 0.9 cases per 100,000 people. In 2023, nearly 187,000 Americans were expected to receive a melanoma diagnosis. Of these cases, more than 97,600 were expected to be invasive melanoma that had grown into deeper layers of the skin.[3][9]
The disease particularly affects younger people. Melanoma is one of the most common cancers in people under thirty years old, especially in young women. Before age fifty, women have higher rates of melanoma than men. However, after age fifty, the pattern reverses and men develop melanoma at much higher rates than women. Men are also more likely to develop melanoma on their trunk, often on the upper back, while women more commonly develop it on their legs.[2][10]
What Causes This Cancer
The primary cause of most melanomas is exposure to ultraviolet light. Research indicates that approximately 86 percent of melanomas are caused by ultraviolet radiation from the sun. When UV light hits the skin, it can damage the genetic material inside cells, specifically the DNA. This damage can cause changes to particular genes that control how cells grow and divide. When the DNA in melanocytes becomes damaged and those cells begin reproducing without normal controls, melanoma can develop.[2][14]
Ultraviolet radiation from tanning beds also significantly increases melanoma risk. Just one indoor tanning session can increase the risk of developing melanoma by 75 percent. Each time a person tans, whether outdoors or indoors, the cumulative damage to the skin increases, raising the risk of melanoma substantially. There is no such thing as a safe or healthy tan. The tanning response itself represents the skin’s attempt to protect itself from damage that has already occurred.[2][23]
When the skin is exposed to UV radiation, specialized cells in the skin called keratinocytes produce a hormone that signals melanocytes to make more melanin. The melanin is then transferred to surrounding cells, where it forms a protective cap over the cell nucleus to shield the DNA from further UV damage. People with darker skin naturally have more of the protective type of melanin, which is why they have lower rates of melanoma compared to fair-skinned individuals.[13]
However, UV light cannot be solely responsible for all melanomas. Some melanomas develop in parts of the body that are never exposed to the sun, including inside the mouth, in the digestive tract, in the eyes, and even on the soles of the feet or under the nails. Current research suggests that a combination of genetic factors, family history, and environmental exposures contribute to melanoma development in these unusual locations.[1][9]
Risk Factors That Increase Your Chances
Several factors can increase a person’s likelihood of developing melanoma. Fair skin that burns easily is a major risk factor. People with blonde or red hair, blue eyes, and pale skin that freckles have significantly higher risk because their skin contains more of a type of melanin that does not protect well against UV damage. However, people with darker skin can also develop melanoma, and when they do, it is often diagnosed at a later stage because both patients and doctors may not be watching for it as carefully.[2][4]
Having many moles or having unusual-looking moles increases melanoma risk. While most moles never become cancerous, the number of moles on the body may help predict the skin’s overall risk. Atypical moles, which are larger than normal moles and have irregular borders or color variation, are associated with increased melanoma risk. Anyone who has previously had melanoma faces a much higher risk of developing another one, sometimes multiple additional melanomas over their lifetime.[1][6]
A family history of melanoma significantly increases risk. If close relatives such as parents, siblings, or children have had melanoma, your risk is elevated. Similarly, a family history of unusual or prominent moles, pancreatic cancer, or certain brain tumors called astrocytomas can indicate increased melanoma risk. Some families carry genetic mutations that make melanoma more likely to develop across multiple generations.[6]
Severe sunburns, especially those occurring during childhood and adolescence, substantially increase melanoma risk later in life. Each blistering sunburn damages the DNA in skin cells and increases the likelihood that melanoma will eventually develop. Lifetime cumulative sun exposure also matters. People who spend many hours outdoors throughout their lives, either for work or recreation, accumulate UV damage that raises their cancer risk.[2][14]
Recognizing the Warning Signs
Knowing how to spot melanoma is crucial because early detection dramatically improves the chances of successful treatment. Melanoma can take several forms. It may appear as a mole, a scaly patch, an open sore, or a raised bump. The appearance varies considerably, which is why it’s important to learn multiple warning signs rather than looking for just one specific pattern.[2]
Doctors use a memory tool called the ABCDE rule to help people recognize suspicious spots on their skin. The “A” stands for asymmetry, meaning one half of the spot does not match the other half. The “B” represents border irregularity, where the edges are not smooth but may be ragged, notched, or blurred. The “C” indicates color variation, with the spot displaying multiple shades of brown, black, gray, red, or white in a mottled or uneven pattern. The “D” stands for diameter, with concerning spots typically being larger than the tip of a pencil eraser, which is about six millimeters across. Finally, “E” means evolving, referring to any spot that is new or changing in size, shape, or color over time.[2][14]
Not all melanomas follow the ABCDE pattern, so it’s important to tell a doctor about any skin changes that seem unusual. Some melanomas may appear as sores that won’t heal, unusual bumps, persistent rashes, or any changes in existing moles. Another useful recognition tool is the “ugly duckling sign.” If one mole on your body looks noticeably different from all your other moles, that ugly duckling should be examined by a dermatologist.[2][14]
Melanoma can develop anywhere on the body, including areas that rarely or never see sunlight. It can appear on the palms of the hands, the soles of the feet, under fingernails or toenails, on the scalp hidden beneath hair, and even inside the mouth or other mucous membranes. Because melanoma in unusual locations is often detected later, it tends to have a worse prognosis than melanoma on sun-exposed skin.[8]
How to Prevent Melanoma
While not all melanomas can be prevented, many cases are avoidable through careful sun protection and lifestyle choices. The foundation of melanoma prevention is limiting exposure to ultraviolet radiation. This means being particularly cautious during the hours when the sun’s rays are strongest, typically between ten in the morning and four in the afternoon. An easy way to gauge when UV exposure is dangerous is to check if your shadow is shorter than you are tall. When your shadow is short, the sun is high in the sky and UV radiation is most intense.[23]
Every time you go outdoors, wearing broad-spectrum sunscreen is essential. Broad-spectrum means the product protects against both UVA and UVB rays. The sunscreen should have a sun protection factor of at least thirty. Apply approximately one ounce of sunscreen, roughly the amount that would fill a shot glass, to all exposed skin about fifteen minutes before going outside. Reapply at least every two hours, and more frequently if swimming, sweating, or spending time near water or snow, which reflect UV rays and increase exposure.[23]
Protective clothing provides excellent defense against UV radiation. Long-sleeved shirts and long pants made from tightly woven fabrics offer good protection. A wide-brimmed hat that shades the face, ears, and neck is important, as these areas are common sites for melanoma. UV-protective sunglasses are necessary not just for comfort but also to protect against eye melanoma, which can develop in the structures inside the eye.[23]
Completely avoiding indoor tanning is critical for melanoma prevention. Tanning beds emit UV radiation that damages DNA in skin cells. No amount of indoor tanning is safe. Young people who use tanning beds face particularly high risk because their skin cells are still actively dividing and growing, making them more vulnerable to UV-induced genetic damage.[23]
Regular self-examination of the skin is an important prevention strategy. Once a month, examine every part of your skin, using mirrors to see your back and other hard-to-see areas. Look for any new spots or changes in existing moles. Taking photographs of your moles can help you track changes over time. Some people find smartphone applications designed for mole mapping helpful for documenting and monitoring their skin. If you notice any concerning changes, see a healthcare provider promptly.[23]
Annual skin examinations by a dermatologist are recommended, especially for people at higher risk. During these visits, the doctor examines the entire skin surface, including the scalp, between the toes, and other easily overlooked areas. Dermatologists are trained to identify suspicious lesions that might not seem concerning to an untrained eye. Early detection through professional skin examinations saves lives.[1]
How Melanoma Changes the Body
Understanding how melanoma affects the body requires knowing what happens when the disease develops and spreads. Normally, melanocytes divide infrequently, less than twice per year. They respond to signals from surrounding cells to produce melanin when the skin is exposed to UV light. When melanoma develops, the melanocytes lose these normal growth controls and begin dividing rapidly and uncontrollably.[13]
In the earliest stage, called melanoma in situ, the abnormal melanocytes remain in the outer layer of the skin. At this stage, the disease has not invaded deeper tissues and has an excellent chance of cure with complete surgical removal. When melanoma begins growing down into deeper layers of the skin, it becomes invasive. The depth of invasion is critically important because it determines the likelihood that the cancer will spread and affects the patient’s prognosis. Deeper melanomas have a higher chance of reaching blood vessels or lymphatic vessels, which can carry cancer cells to other parts of the body.[3][10]
Melanoma spreads through a process that involves several steps. Cancer cells from the primary tumor must first invade through the layers of skin and enter either lymphatic vessels or blood vessels. These cells then travel through the circulatory system and must survive the journey. When they reach a new location, they must exit the vessels, establish themselves in the new tissue, and begin growing. This process is called metastasis. Melanoma most commonly spreads to nearby lymph nodes first, then to distant sites such as the liver, lungs, bones, and brain.[3]
When melanoma spreads to lymph nodes, patients may notice swollen, firm lumps in areas such as the armpit, groin, or neck, depending on where the original melanoma was located. When it reaches distant organs, symptoms depend on which organs are affected. Melanoma in the lungs might cause shortness of breath or persistent cough. Melanoma in the liver can cause abdominal pain and jaundice, a yellowing of the skin. Melanoma in bones may cause pain in the affected areas. Brain metastases can cause headaches, seizures, or changes in thinking and behavior.[8]
Some characteristics of the original melanoma help predict whether it is likely to spread. Ulceration, meaning the skin over the melanoma has broken down, indicates a more aggressive cancer. The mitotic rate, which measures how rapidly the cancer cells are dividing, is another important factor. Melanomas with high mitotic rates are more likely to metastasize. The presence of cancer cells in lymphatic or blood vessels in the tissue around the melanoma also indicates higher risk of spread.[3]
