The most common form of cancer in the United States is skin cancer, which—if you think about it—makes sense. As our largest organ and shield from the elements, skin is continually exposed to the sun’s ultraviolet rays. You might think that noticing the deadliest type, melanoma, would be as simple as spotting a dark, bumpy mole. But with melanoma, it’s not always that simple.

First, a crash course on what melanoma is. “Melanoma is a cancer of melanocytes, the skin cells that produce melanin pigment, which gives skin its color,” says Nima Gharavi, MD, PhD, FAAD, FACMS, the director of dermatologic surgery at Cedars-Sinai Medical Center. “It’s one of the most dangerous types of skin cancers, because if detected late, it has the potential to spread to other organs and can result in death.” Melanoma is typically caused by the kind of intense, intermittent sun exposure that leads to sunburns. (Tanning beds are also highly associated with a higher skin cancer risk.)

Unfortunately, cases of melanoma are increasing—and fast. According to the American Academy of Dermatology (AAD), more than 100,000 new melanoma cases were diagnosed in 2021. Since 2012, the number of new invasive melanoma cases diagnosed annually has increased by 31 percent. “Melanoma is more common in people with fair skin who have less melanin to protect them from the sun,” says Dr. Alam. Still, melanoma can an affect anyone regardless of skin color.

Melanoma can appear as a mole on the surface of the skin, but even areas rarely exposed to the sun are at risk. You should see a dermatologist if you notice moles with any of these characteristics: asymmetry, irregular shape, change in appearance, poorly defined border, color variation and increased size. “When [a mole] looks abnormal, we want to do a biopsy to see if there are melanoma cells or if it’s something on the way to becoming melanoma,” says Murad Alam, MD, Vice Chair and Chief of Cutaneous and Aesthetic Surgery in the Department of Dermatology at Northwestern Medicine. The good news? Melanoma is highly curable as long as it’s caught in the beginning stages.

Surprising spots you’re probably not checking

Melanoma can show up on your ears, scalp, genitalia, soles of your feet, palms, nail beds, fingers, and toes. It takes longer to recognize melanoma in those areas because they are often overlooked or difficult to monitor. “Sometimes melanoma doesn’t have pigment, so you don’t biopsy it,” says Dr. Alam. Without early detection, the melanoma can spread. “The melanoma grows downwards into the skin, and it can break off and travel through the blood or the lymph nodes anywhere in the body,” he says. “As the melanoma goes deeper into the skin, it becomes more dangerous.”

How to monitor melanoma

Some areas of the body, like your scalp and back, are hard to inspect, so another set of eyes are important. Doctors recommend scheduling an annual full-body skin exam by a board-certified dermatologist, particularly if you have risk factors such as fair/freckled skin, red hair, a large number of moles, a history of multiple sunburns, or a personal or family history of atypical moles or melanoma. “We want to see people every year to check for melanoma, starting at age 18—especially if you have fair skin,” Dr. Alam says. “An annual visit can be as fast as a few minutes.”

At home, do a skin self-exam once a month. Stand in front of a full-length mirror with a handheld mirror and look at your body. Check any moles, blemishes, or birthmarks from head to toe. You’re looking everywhere—under your breasts, between your toes, behind your ears. If you notice changes, call your dermatologist. “Even if it doesn’t fit all the criteria of being abnormal, the fact that it’s changing is useful information that may motivate the doctor to do a biopsy,” says Dr. Alam. When you look at your skin regularly, you’ll know what’s normal for you, adds Dr. Gharavi. (His tip: Photograph your moles to document your baseline.

Sunscreen isn’t just for beach days

“Skin cancer prevention requires a comprehensive approach to protecting yourself against harmful UV radiation,” says Dr. Gharavi. “The sun’s UV radiation reaches you even when you’re trying to avoid it—penetrating clouds and glass, and bouncing off snow, water and sand.” That’s why, even in the middle of winter on a cloudy day, you should wear sunscreen—especially on your face, says Dr. Alam. It’s a worthwhile habit to outsmart the sun and help keep cancer away. Along with sunscreen, here are other ways to shield your skin:

• Seek shade, especially between 10 a.m. and 4 p.m.
• Stay out of the sun when the UV index is high.
• Avoid tanning and never use UV tanning beds.
• Cover up with sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses.
• Use a broad-spectrum (UVA/UVB) sunscreen with an SPF of 15 or higher every day. For extended outdoor activity, use a water-resistant, broad-spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher and ingredients zinc or titanium to block out sun.
• Apply 1 ounce (2 tablespoons) of sunscreen to your entire body 30 minutes before going outside. Reapply every two hours or after swimming or excessive sweating.

While completely eliminating your melanoma risk is impossible, being sun-smart and scheduling annual mole checks can go a long way in keeping your skin—and the rest of your body—healthy for the decades to come.