Some cancer patients took a deworming medicine to cure their disease but suffered side effects, the Korean Society of Medical Oncology (KSMO) said. The group plans to collect similar cases and inform cancer patients about the risk of taking anthelmintic drugs.

The controversy over the effectiveness of dewormers for cancer grew after a YouTube video claimed that a U.S. terminal cancer patient achieved complete remission after taking fenbendazole, a dog anthelmintic. As the video went viral, fenbendazole-containing dog worm pills went out of stock.

From left, Korean Society of Medical Oncology 2019 Chairman Kim Tae-won, KSMO President Jang Joung-soon, and KSMO 2019 Scientific Program Committee Chair Im Seok-ah hold a news conference at a hotel in Seoul, on Thursday.

The Ministry of Food and Drug Safety on Oct. 28 warned cancer patients against taking fenbendazole, saying the drug was authorized only for animals and that it was improper for cancer patients to use it. However, the warning failed to contain cancer patients’ desire to use the unusual treatment.

Cancer patients are now rushing to purchase other anti-worm medications from abroad amid rumors that albendazole and mebendazole, which have a similar chemical structure with fenbendazole, could have an anti-cancer effect.

To continue its warning against the risk of taking unauthorized routes of treatment, KSMO held a news conference during its annual meeting and international conference KSMO 2019 at a Seoul hotel on Thursday.

KSMO physicians said they had seen cases where cancer patients suffered side effects after taking dewormers.

“Among patients who took the deworming drug, some came to the emergency room due to intestinal necrosis and got hospitalized,” said Kim Tae-won, chairman of KSMO 2019, also a professor of Oncology Department at Asan Medical Center.

“No matter how strongly we emphasize that taking fenbendazole is dangerous, cancer patients do not seem to listen to us. However, we see actual cases of side effects. So, our society will collect side effect cases and inform them in detail what kind of side effects they could suffer from taking a dewormer,” he added.

Oh Do-youn, secretary-general of KSMO 2019 and a professor of Hemato-Oncology Department at Seoul National University Hospital, said many chemical substances have the same mechanism even though not all of them are used as anti-cancer drugs.

To use them as drugs for cancer, they have to go through numerous procedures from clinical trials to approval, but anthelmintic drugs have not undergone the necessary procedures, she said.

The annual meeting KSMO 2019, which continued through Friday, was arranged as an international conference for the first time in the history of KSMO.

William Kaelin, a professor of medicine at Harvard Medical School who won the 2019 Nobel Prize in Physiology or Medicine, attended the event, drawing much attention.

Professor Kaelin won the Nobel Prize for discovering how the body’s cells sense and react to oxygen levels.

At the conference, he gave a lecture on the interaction between hypoxia-inducible factors (HIFs) and von Hippel–Lindau (VHL) tumor suppressor gene, and new drug development targeting HIFs.

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