Skin cancer myths

A tan is a sign that UV rays have already injured the skin. The American Academy of Dermatology states plainly that a base tan cannot prevent sunburn, and people who build one before a trip still burn. Tanned skin still takes on more DNA damage with each exposure, so shade, clothing, and sunscreen do the protecting.

Skin cancer occurs in every skin tone. In people with darker skin it often shows up in places that get little sun, such as the palms, soles, nails, and inside the mouth, and doctors often find it at a later stage. The American Cancer Society puts the lifetime risk of melanoma at about 1 in 1,000 for Black people and 1 in 200 for Hispanic people, compared with about 1 in 33 for white people. Lower risk still means some risk, and a late diagnosis makes treatment harder.

Clouds block far less UV than they seem to. The American Academy of Dermatology says up to 80% of the sun's UV rays can pass through cloud cover. Winter adds its own exposure: the World Health Organization notes that fresh snow reflects about 80% of UV radiation, which can nearly double the dose a person receives, and UV levels rise about 10% with every 1,000 meters of altitude.

Ordinary glass stops most UVB, the rays that cause sunburn. UVA rays pass through window glass, and UVA also damages skin cells and contributes to skin cancer. The Skin Cancer Foundation notes that car windshields are treated to filter some UVA, while side, rear, and sunroof glass usually are not. A long daily commute or a desk beside a sunny window adds up over years.

SPF measures how much UV energy it takes to burn protected skin compared with bare skin. The FDA states that SPF does not translate into hours of safe time in the sun, because UV strength changes with the time of day, the location, and how much sunscreen you put on. SPF 30 already filters about 97% of UVB rays, and no product filters 100%. Every sunscreen wears off, so dermatologists advise reapplying about every 2 hours and after swimming or sweating.

UV radiation is a proven cause of skin cancer. FDA studies found that 4 common sunscreen ingredients can be absorbed into the bloodstream, and the researchers stressed that absorption alone does not show harm. The FDA has asked manufacturers for more safety data and, in the meantime, tells people to keep using sunscreen. Anyone who prefers to avoid those ingredients can choose a mineral sunscreen made with zinc oxide or titanium dioxide.

Skin does make vitamin D in sunlight, but the same UVB rays that trigger it also damage DNA. The American Academy of Dermatology states that no level of UV exposure gives you maximum vitamin D without raising skin cancer risk. Food and supplements work without that cost. Most adults need 600 IU a day, and adults over 70 need 800 IU, amounts that fatty fish, fortified milk, fortified cereals, or a supplement can supply.

In 2009 the World Health Organization's cancer research agency (IARC) placed UV tanning devices in Group 1, its highest category, meaning they cause cancer in humans. Its review found that melanoma risk rises by 75% when people start using tanning devices before age 30. Tanning beds give off mostly UVA, so they are also a poor way to make vitamin D, which depends on UVB.

Risk does climb with age, and the average age at a melanoma diagnosis is 67. Still, the American Cancer Society lists melanoma among the most common cancers in people younger than 30, especially young women. Before age 50, women have higher melanoma rates than men. A new or changing spot deserves a look at any age.

Most melanomas appear as a new spot on skin that looked normal before. A 2017 meta-analysis in the Journal of the American Academy of Dermatology (Pampena and colleagues) pooled 38 studies and found that about 29% of melanomas arose from an existing mole, while about 71% arose on their own. Watching your moles matters, and so does noticing any new mark that looks different from the rest.

Most early skin cancers cause no pain at all. The American Academy of Dermatology notes that for many people the only sign is a new or changing spot, and many patients with early disease feel fine. Itching, tenderness, bleeding, or numbness can occur, but waiting for pain often means waiting too long. Change over time is the more reliable warning.

Sun-exposed skin is the most common site, yet skin cancer can grow anywhere. Acral melanoma develops on the palms, the soles, or under a nail, and the American Cancer Society notes that it makes up a large share of melanomas in people with darker skin. Melanoma can also start in the eye, the mouth, and the genital or anal area, though those sites are much less common. A full skin check includes the scalp, between the toes, and the nails.

The National Cancer Institute calls the chance that surgery will spread cancer extremely low. Surgeons follow standard steps to prevent it, such as using separate instruments for each area when they sample more than 1 site. Skipping a biopsy carries a far bigger risk: a cancer that keeps growing without a diagnosis.

Many skin cancers are cured with a minor procedure, and that fact hides the exceptions. The American Cancer Society estimates about 8,510 melanoma deaths in the United States in 2026. Merkel cell carcinoma, a rare type, grows fast and spreads far more often than the common types. Even basal and squamous cell cancers, which seldom spread, can destroy nearby tissue on the nose, eyelid, or ear when left to grow.