Current Melanoma Epidemic Caused by Old Medical Beliefs

AMSTERDAM ― The current epidemic of melanoma in light-skinned individuals is the result of old-fashioned medical beliefs about the health benefits of ultraviolet light (UV) and the practice of "heliotherapy" in the first half of the twentieth century, say French researchers.

A statistical analysis of melanoma mortality points the finger clearly at this practice, which involved exposing young children to intense UV radiation in the hope of preventing rickets and for other supposed health benefits.

The findings were presented here at the inaugural European CanCer Organisation (ECCO) Congress 2017 by a group led by Philippe Autier, MD, from the International Prevention Research Institute in Lyon, France.

The same analysis shows that melanoma death rates are decreasing in younger individuals as a result of sun protection practices, and the team predicts that melanoma deaths will become rare in people younger than 50 years.

"This is great news, as it shows that our efforts at prevention are working," commented ECCO President Peter Naredi, MD, from Sahlgrenska Academy at the University of Gothenburg, Sweden, speaking at a press briefing at which the findings were highlighted.

Dramatic Increase in Melanoma Deaths

In the early 1900s, melanoma was rarely mentioned as a cause of death in the medical literature, the researchers noted.

There was a dramatic increase in melanoma deaths in all light-skinned populations from the 1950s to the 1980s, they noted.

In the 2000s, melanoma mortality rates are still increasing in individuals aged 70 years or older, but they are plateauing in the 50- to 69-year-old group, and they are decreasing in individuals younger than 50 years.

"Such contrast in trends between age groups is the hallmark of substantial changes in successive generations in the exposure to an agent able to trigger deadly melanoma," they comment.

Statistical analyses demonstrate that most of the exposures associated with deadly melanoma had to have taken place from 1910 to 1950.

This is exactly the era when heliotherapy was popular.

This involved exposing young children to strong UV light – and children were undressed, so there was active exposure of most of the skin surface. UV light was delivered by carbon arc and quartz mercury arc lamps, or children were exposed to strong sunlight, as shown in old photos that the team displayed in their poster presentation.

There was no barrier protection; only goggles were used to protect the eyes.

"At the time, there was complete ignorance about the carcinogenic effects of UV radiation," the researchers noted.

Vogue for Heliotherapy

By 1920, heliotherapy had become widespread in all light-skinned individuals, and there was a widespread belief among healthcare professionals that UV light was beneficial, the researchers noted.

Some of the popularity for UV therapy was driven by the discovery that UVB was essential for the endogenous synthesis of vitamin D, which led to its being used for the prevention and treatment of rickets (which is due to vitamin D deficiency). Beliefs about benefits were also boosted by observations that exposure to UV light could heal some skin infections, so UV light was considered bactericidal and was used for tuberculosis patients.

But there was also an exaggeration of the benefits, the researchers suggested. "The keen interest of many health professionals led to an inflation of claims on preventive and curative effects of UV radiation," they commented. This led to many indoor heliotherapy units in medical facilities and to the commercialization of small UV-emitting lamps for private use.

From about 1910 to 1960, many children were exposed "for the sake of preventing rickets or improving health," the researchers noted.

"It was common for babies and schoolchildren to be treated with commercial UV radiation–emitting devices and exposed, unclothed, to the midday sun," Dr Autier commented in a statement.

The popularity of heliotherapy began to wane after the Second World War (which ended in 1945), the team noted. "The fashion faded in the 1960s as effective treatments, such as vaccine and antibiotics, became available," Dr Autier commented. There was also a growing recognition that sun exposure and sunburn in childhood cause irreversible damage to the skin and are strong risk factors for skin cancer in adult life, he added.

Sun protection of light-skinned children began in the 1980s in Oceania and has become increasingly common, the researchers noted.

"The disappearance of the heliotherapy vogue in the 1960s and the increase in sun protection of children afterwards is the main cause of declining melanoma mortality," they concluded.

Death Rates From Melanoma Are Decreasing

Death rates from melanoma have peaked and are now falling, Dr Autier and colleagues reported. They found that death rates from melanoma peaked in around 2005 for US men and in 1995 for US women. In Sweden, it peaked in around 2010 for both sexes. In Australia, it peaked in 2015 for men and in 1990 for women.

Using a statistical model, the researchers predicted that in 2050, the rates of melanoma deaths in the United States would be 2.5 to 3 times lower than in the peak years, falling back to rates that prevailed before 1960.

The age-standardized death rate will have fallen from the current 4 per 100,000 men in the United States to around 1.6 per 100,000 in 2050, assuming there is no effective treatment, and will fall to 1.1 per 100,000 in 2050 if there is an effective treatment and everyone has access to it.

Although the rate of deaths is decreasing, the number of deaths is continuing to rise because of the aging of the population.

"As time passes, melanoma deaths will become steadily rarer in people younger than 50 years old, and after 2050, practically all melanoma deaths will occur in people over the age of 70," Dr Autier commented.

"Our findings clearly show that most of the death toll due to melanoma has been caused by medically backed exposures to highly carcinogenic UV radiation between 1900 and 1960," Dr Autier said.

"They also show that UV protection of children pays off, because the rates of melanoma death keep going down from around 1960 to the current day, as the UV protection of children based on clothing, shading, and avoidance of excessive sun exposure has spread in most light-skinned populations, beginning in Australia," he added.

Commenting on the findings in a press statement, Dr Naredi said: "If the predictions are right, protection from sun exposure is one of the best examples of primary prevention, and this study proves all efforts to protect a population from unhealthy amounts of sun exposure are worthwhile."

European CanCer Organisaton (ECCO) Congress 2017. Abstract 1201. Poster presented January 28, 2017; oral abstract 1144 presented January 29, 2017.

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Cite this: Current Melanoma Epidemic Caused by Old Medical Beliefs - Medscape - Jan 30, 2017.