"Useless" chemotherapy, demonization of sugar or "alternative" treatments: false information about cancers can seriously harm patients, causing delays in care, complications and even death, warn professionals and associations.
"It's a daily problem," Dr. Mario Di Palma, a medical oncologist at the Gustave-Roussy Institute in Villejuif (Val-de-Marne), told AFP.
While the impact of misinformation remains difficult to quantify, this seasoned practitioner often debunks false beliefs, primarily "around diet, fasting, and dietary supplements." Many patients want to cut out sugar, "because they've read on social media that it feeds tumors"—which is false.
"Patients are looking for levers they can use, and diet is one of them, but we must remain cautious," points out Emilie Groyer, PhD in biology and editor-in-chief of the website of the magazine of the association Rose Up, which supports women with cancer.
A strict diet risks "weakening" patients: if they are malnourished, "patients tolerate treatments less well, have to reduce doses, and this affects their prognosis," she explains, mentioning a member who was fasting and, too tired, had to suspend her treatment.
Hoping to counteract side effects from treatments or improve their well-being, many people affected by cancer also resort to dietary supplements, often without medical advice, according to several oncologists.
However, these supplements can disrupt the body's elimination of certain treatments.
– Loss of opportunity –
"At Gustave-Roussy, we have several people every year who develop kidney failure or hepatitis due to an interaction between a food supplement and an anti-cancer drug," says Dr. Di Palma, emphasizing the need for a climate of trust with the patient.
"It was trust and support in integrative oncology that I lacked," Christine (who only gives her first name), 57, who has breast cancer, told AFP.
When she relapsed in 2021 and learned of the existence of metastases, she agreed to an ovary removal but then refused hormone therapy with targeted therapy because she felt "too weak".
She then tried other methods – not scientifically proven. “I changed my diet, cut out sugar, and drank vegetable juices,” she describes. After two years of feeling “better,” she explains, her condition deteriorated again, forcing her to resume medical treatment.
“Beware of the time factor,” warns Caroline Mercier, general manager of Rose Up, “when you spend several months taking supplements, self-medicating, and postponing treatments, the loss of opportunity is very significant.”
More vulnerable, people with cancer are also "the preferred targets of malicious individuals or more structured movements", warns Hugues Gascan, president of the Study Group on Sectarian Phenomena (GéPS).
– Purges and eating raw food –
He urges us not to "dissociate therapeutic drift from sectarian drift," citing as an example "Germanic medicine," promoted by Ryke Geerd Hamer and based on the false idea that cancer stems from a "psychological knot." This approach has given rise to "biological decoding or cellular reprogramming, sold as a cancer cure," he notes.
Mr. Hamer, who died in 2017, was convicted in 2004, notably for complicity in the illegal practice of medicine, following a complaint from a man whose wife, "suffering from breast cancer, died after refusing proven treatments," notes the latest report from the Interministerial Mission for Combating Sectarian Abuses (Miviludes).
Camille suffered a similar "drift", according to the account given to AFP by her cousin Laura (names changed).
After the announcement of her breast cancer, Camille consulted a naturopathic expert. "She told her that cancer didn't exist, that it was just toxins that could be eliminated with cleanses, essential oils, and by eating raw," says Laura.
Camille left with a "pseudo-prescription of oils and a specific diet," but her condition deteriorated rapidly, her weight plummeted, and her pain became unbearable. After two years, she returned to the doctor, but "it was already too late," says Laura, whose cousin would die a few years later.
Hence his desire to warn about the risks of abuses: "The victims are not guilty, but victims of professional fraudsters."
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