The top risk factor for melanoma is exposure to ultraviolet (UV) light from the sun or indoor tanning beds or booths. Many skin melanomas are thought to occur as a result of sunburns or excessive exposure to UV light over time.
That said, it’s also possible for melanoma to develop in parts of your body not exposed to sunlight, such as the bottoms of the feet and the membranes lining the eyes, sinuses, anus, and vagina. These are rare conditions, and doctors are still trying to understand why they occur.
In addition to UV light exposure, there are several other risk factors for melanoma.
The risk for melanoma increases with age. Most melanoma occurs in older people. Children are rarely affected.
People with moles that are unusually large, irregularly shaped, poorly defined along the edges, multiple colors, or flat and bumpy are significantly more likely to develop melanoma. Sometimes these types of moles run in families.
Having an increased number of moles, even if they appear normal, is associated with an increased risk for developing melanoma.
Large/Giant Congenital Moles (Birth Marks)
Having unusually large moles at birth is a possible precursor to melanoma. The risk varies according to the size of the mole. Bigger moles pose a greater risk.
Personal or Family History of Melanoma
If you’ve already been diagnosed with melanoma, you have a much higher risk of developing it again. You’re also at a higher-than-average risk for melanoma if your parents or siblings have had it.
Some people inherit a genetic mutation that makes them more likely to develop melanoma. One example is the CDKN2A mutation. If you have a strong history of melanoma in your family, your doctor may suggest that you and your family members get tested for these mutations. Finding out that you have a mutation may help you make decisions that can lower your risk for developing melanoma.
People with any skin color can develop melanoma, but having a light complexion puts you at a significantly higher risk. This means light eyes, light hair, or prominent freckles. People with a light complexion also tend to sunburn easily.
People of color rarely develop melanoma from UV light, because dark skin has melanin that filters the UV. Melanoma can develop in any color skin though, including black, brown, and olive, and it can start in places that get little sun. It’s important to stay alert to skin changes, talk with your doctor, and have your skin examined if you notice suspicious changes.
Ways to Prevent Melanoma
Your best defense against melanoma and other skin cancers is to limit your exposure to ultraviolet (UV) light. Exposure to UV light is the only known preventable cause of melanoma.
Here are a few steps you can take to limit your risk of melanoma:
- Avoid staying outdoors for long periods of time. Seek shade whenever possible, even if you are wearing sunscreen. This applies especially to the middle of the day, when the sun is at its most intense.
- Wear clothing that can block the sun. This includes long-sleeved shirts, pants, and wide-brimmed hats. Because dark clothing tends to absorb more UV rays than light clothing, it better protects your skin. Also look for clothing made from fabric with built-in sun protection. Look for items with an ultraviolet protection factor (UPF) of 50 or greater.
- Use broad-spectrum sunscreen with an SPF of 30 or above. (“Broad spectrum” means that it protects against the two forms of UV rays: UVA and UVB. Look for this term on the label — it should be clearly marked.)
- Avoid tanning and sunburns. Tanning is the body’s response to injury caused by UV rays. Indoor tanning beds and booths are also dangerous sources of UV radiation and should be avoided.
- Wear sunglasses with UV protection when you’re outside.
Stay Alert to Skin Changes
Pay attention to any changes in your skin. Inspect your skin on a regular basis, particularly if you have risk factors for developing melanoma.
Once a month, examine your skin in front of a mirror. Look closely from head to toe for changes in existing moles or the appearance of new ones. Use the Do U C Melanoma method to look for suspicious skin changes. Also talk with your doctor about setting up regular skin screenings with a dermatologist and other early-detection methods. Learn more about melanoma surveillance options at MSK.
If you notice suspicious changes in your skin, talk with your doctor. Your best chance for a good overall result is to have your skin examined and treated right away.