Most people have 10 to 40 moles — small, dark brown spots — on their body. Although most moles are harmless, they can become cancerous in rare cases.
Luckily, skin cancers, like melanoma, are usually highly treatable. When certain melanomas are found and treated before they spread to the lymph nodes, there is a 99% five-year survival rate.
Learning about moles and other skin lesions — areas of skin that look different from the rest of your skin — can help you recognize the signs of skin cancers, including melanoma.
What causes moles?
Your skin has several kinds of cells. Melanocyte cells produce melanin, a pigment that gives your skin its color. Normally, melanocytes are evenly distributed throughout your skin. When melanocytes cluster together in one place, they form a mole. Melanoma is a cancer that develops when melanocytes develop DNA mutations.
When should I get a mole checked?
Catherine A. Degesys, M.D., is a dermatologist, Mohs micrographic surgeon, and dermatologic oncologist at the Mayo Clinic recommends: “People with a personal or family history of skin cancer, risk factors such as extensive sun exposure, blistering sunburns or tanning bed use, or those who have suspicious-looking lesions should come in for an exam. That way, we can screen for early detection of all types of skin cancers, including melanomas. Patients who are immunosuppressed should also be evaluated frequently as this can increase their risk of skin cancers.”
There are two main categories of skin cancer: melanoma and nonmelanoma skin cancer. Within the nonmelanoma skin cancer category, the two most common types are basal cell carcinoma (which is also the most common type of cancer worldwide) and squamous cell carcinoma.
Signs of atypical moles and melanoma
“When it comes to pigmented lesions — like moles and melanomas — we commonly tell people to remember A, B, C, D and E,” says Dr. Degesys.
- A is for asymmetric lesions. Typical moles are round instead of oddly shaped. “If you put a mirror right in the middle of the mole, you should see an equal image on both sides,” Dr. Degesys says.
- B is for border. It should be easy to see where your mole starts and stops. “You want your moles to have a crisp, clean border where you have pigmented skin and then nonpigmented skin instead of a scalloped or ill-defined border.”
- C is for color. A mole should be only one color. “We want moles to be homogenous in color, not incorporating multiple colors like blue, black, red and brown,” explains Dr. Degesys. “You also want your moles to look overall pretty similar to each other. So, if you have a mole that’s a different color than the rest of your moles, that may indicate that it needs to be evaluated.”
- D is for diameter. Keep an eye on large moles. “Any mole with a diameter larger than the size of a pencil eraser should be checked out.”
- E is for evolution. With moles, change is not a good thing. “Any mole that’s increasing in size or evolving in any way, such as color, size or shape, or new symptoms should be examined,” says Dr. Degesys.
Signs of nonmelanoma skin cancers
According to Dr. Degesys, nonmelanoma skin cancers often present with “lesions that show up on the skin that people may think are pimples that don‘t go away. They may bleed easily or just not heal. They may be scaly, painful or increasing in size. Those types of skin lesions need to be checked too.”
What is the procedure for melanoma screening like?
If you have a suspicious mole, don’t be afraid to go to your primary care team or the dermatologist. The screening is generally easy and pain-free.
“Typically, dermatologists start with a full body scan exam, so we can compare your suspicious lesion to your other lesions to get a baseline,” explains Dr. Degesys. “We often employ a tool called a dermatoscope, which allows us to magnify the lesion and look at it in higher detail.”
If the lesion needs further evaluation, your healthcare professional will probably suggest a biopsy.
She continues: “During the biopsy, we will numb the area with lidocaine. It’s similar to what you have at the dentist for cavities. Then we take a small sample of the skin and submit that to the lab for evaluation.”
How common is melanoma, and what are the risks?
Skin cancer is the most common cancer in the U.S. There are several types of skin cancer, but melanoma is known to be most dangerous because it spreads more easily to other areas of the body.
Around 100,000 people will be diagnosed with invasive melanoma in the U.S. this year. In 2022, experts estimated that 7,650 people in the U.S. died of melanoma — 5,080 men and 2,570 women.
Dr. Degesys says melanoma risk factors include:
- Having skin cancer in the past.
- Having first-degree relatives (like parents or siblings) who have had melanoma.
- A history of tanning bed use or blistering sunburns.
- Having a lighter skin color.
- History of immunosuppression or reduced immune system.
Additionally, some emerging research shows that having an increased number of moles — or an increased number of clinically atypical moles — raises your risk of melanoma.
Does skin color affect melanoma risk?
Having lighter skin tones is a significant risk factor for melanoma. However, people with darker skin tones can get melanoma too. While only 1 out of 1,000 Black individuals gets melanoma, they are usually diagnosed when the cancer is in its later stages, when it’s harder to treat.
“Skin cancer can develop in all skin types, so even patients with darker skin types should protect their skin and see a doctor for any suspicious lesions,” says Dr. Degesys.
Should I remove all my moles if I’ve already had melanoma?
Cancer is scary. If you’ve already had melanoma, you might be tempted to get all of your other moles removed to avoid future cancers.
But Dr. Degesys says it’s not necessary.
“There’s really no clinical evidence that we should remove every pigmented lesion on a person who’s had a history of melanoma because, in reality, only about a third of melanomas actually arise from preexisting moles,” she says.
She continues, “Just because you’ve had a history of melanoma, or even if you have a strong family history of melanoma, that does not mean you need to remove all your moles. Even though it’s a relatively simple procedure, there are always risks and benefits. In that case, the risk would exceed the benefit.”
How can I avoid skin cancer like melanoma?
If you want to avoid skin cancer, limiting your exposure to ultraviolet (UV) radiation from sunlight is critical.
Dr. Degesys says there are standard things you can do to prevent sun exposure, including:
- Stay out of the sun during times when the sun is strongest.
- Wear wide-brimmed hats, sunglasses, long-sleeved shirts or rash guards when possible.
- Apply sunscreen often, reapplying every 80 to 120 minutes — or more frequently if you’ve been swimming or sweating.
- Apply enough sunscreen. Use a full shot glass of sunscreen every time you reapply.
- While sunscreen lotions and sprays are likely similar in efficacy, it’s harder to know if you’re applying enough sunscreen with a spray.
When using sunscreen, Dr. Degesys suggests: “Pay careful attention to the areas of your body that are highly sun-exposed. Your head and neck are obvious, but people forget about arms, hands, lips and ears. These are common places we treat for skin cancers because people don’t remember to apply sunscreen on those areas of the body.”
What sunscreen SPF level is recommended to avoid skin cancer?
SPF — sun protection factor — tells you how effectively a sunscreen blocks harmful ultraviolet radiation.
Dr. Degesys says: “Once you get past an SPF of 30 the difference is really within a couple of percentage points as far as how effectively it blocks the sun. For example, SPF 30 is 97% effective at blocking the UV rays, while SPF 50 is about 98%.”
She adds, “What’s important to remember is that the number of the SPF does not pertain to the length of time that it’s effective. Sometimes, people think if they put on SPF 100, they should be good all day. But SPF has nothing to do with the length of time you’re protected.”
How often should I see my dermatologist?
“If you have a strong family history or a personal history of skin cancer, then I would say to come in at least annually,” says Dr. Degesys. “There are some scenarios where we have patients screened more regularly. For example, if you’ve had a recent melanoma or other high-risk factors. Some types of blood cancers or organ transplants increase your risk of skin cancers. But, in general, about once a year is sufficient.”
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