Social media posts claim skin cancer has only emerged in the past 60 years and is primarily attributable to factors other than sun exposure, such as diet and sunscreen use. These claims are false; there is a long historical record of skin tumors — and studies indicate the vast majority result from too much ultraviolet radiation.
“Skin cancer is a relatively new phenomenon in the last 60 years or so and yet our ancestors for hundreds of years have been living outdoors, working outdoors, and they didn’t get skin cancer,” says a woman in a Facebook reel posted July 29, 2023.
The speaker also claims a study on animals showed those with a “highly nutritious diet” did not develop cancer when exposed to the same radiation as a group on a “standard American diet,” of which 25 percent got skin cancer.
But the notion that skin cancer is relatively new is false — medical journal records indicate the disease has existed throughout history, even if the same terms were not used.
Cancer was described in Egyptian papyri as early as 2500 BC, according to the Journal of the American Academy of Dermatology (archived here). Hippocrates used the term melanoma — the most dangerous form of skin cancer — in the fifth century BC (archived here).
The French physician Rene Laennec wrote about melanotic lesions in 1804. Researchers also described other forms of skin cancer, such as basal cell carcinoma in 1827 and squamous cell cancer in 1912 (archived here and here).
“It’s not sensible to say it’s been around for only 60 years. That’s simply not true.”
However, skin cancer rates have been rising in recent decades. Sarnoff pointed to factors such as an aging population, better detection and diagnosis, the use of tanning beds, the depletion of the ozone layer and a false sense of security from sunscreen use.
“People may not use enough sunscreen, they may not apply it properly and they may not reapply after two hours — and they feel they are protected when they are not,” she said.
The claims shared on social media are based on what Day describes as a Baylor University study.
“They took two groups of experimental animals. They gave one the standard American diet, which is terrible. They gave the other one a highly nutritious diet. Then they expose both groups of animals to the ultraviolet rays of the sun,” she says in the video.
“In the group on the standard American diet, 25 percent got skin cancer. In the group on the highly nutritious diet not one animal got skin cancer.”
But AFP found no trace of the research.
“There is no record of such a study having been conducted at the institution,” a Baylor University spokesperson said in an August 3 email.
Sarnoff of the Skin Cancer Foundation told AFP that a nutritious diet is important in maintaining cellular health, which can help prevent various forms of cancer. But there is no evidence specific foods cause or avert skin cancer.
She added that “most of the cancers, especially the squamous and basal cell, are on sun-exposed areas of the body.”
“It’s rare to find these in other areas,” Sarnoff said.
A 2014 study (archived here) found about 90 percent of non-melanoma skin cancer and 65 percent of melanoma cases were associated with ultraviolet radiation, mostly from the sun. A separate UK study (archived here) found an even higher association between sun exposure and melanoma.
Some of the social media posts suggest a diet high in certain vegetable or seed oils — which have previously been the subject of misinformation — is a key factor in skin cancer. But the nonprofit World Cancer Research Fund found no such association (archived here).