'Dog dewormer is not a cure all': experts warn of cancer treatment myth

By Bahk Eun-ji

The buying up of cheap dog deworming medicine has been continuing despite strong warnings by doctors and the government regarding potential side-effects of taking it as an anticancer drug.

Following the controversy over the claimed anticancer effects of fenbendazole, a drug used by veterinarians to protect against gastrointestinal parasites in dogs, cats, horses and cattle, after an online video claimed that the medicine could cure cancer went viral last year, another rumor about albendazole, which has a similar chemical structure to fenbendazole has spread online with similar claims that it can be used as a treatment for allergic rhinitis.

In early April, pharmacists here warned the public against taking Ivermectin, an anti-parasitic drug which had been rumored to be effective in treating COVID-19. Various media outlets reported on Ivermectin's possible use as a COVID-19 treatment after reading a collaborative study on the drug led by the University of Melbourne and Royal Melbourne Hospital in Australia.

The Korean Pharmaceutical Association (KPA) said however, it has not been officially verified whether the drug is effective in killing the COVID-19 virus (SARS-CoV-2) in people.

At the time of the recent tap water incidents in which worm-like creatures were discovered, the stock price of pharmaceutical companies that produce related medicine suddenly surged.

Some of the most easily found drugs in domestic pharmacies include fenbensazole, albendazole and fluvendazole. These are mainly used for roundworm, pinworm, flatworm, and hookworm infections which can be caused by raw vegetables. When the medicine enters the human body, it binds to microscopic proteins and inhibits the absorption of glucose by the parasite. It is a method of starving adult insects, eggs, and larvae by blocking the energy supply. However, it is rarely absorbed into the organs of a human host.

Video clips on YouTube and various online communities have attracted attention after posting testimonials regarding drugs including fenbendazole and albendazole in treating diseases including cancer, diabetes and hemorrhoids, but the Ministry of Food and Drug Safety and the Korean Cancer Association (KCA) once again said there is a lack of clinical data to vouch for their safety and efficacy.

The anticancer effects of those medicine are mainly based on the mechanism of microtubule destabilization. The argument for the anticancer effect was based on the results of cell and animal experiments to determine if the ingredients of the anthelmintics suppress the micro-organisms involved in the cytoskeleton, cytotropism, and the division of cells within people and animals, thus preventing cancer cell proliferation. However, experts say that it is not a clinical trial for people and poses potential dangers.

One Swedish clinical trial was conducted in 2018, but it was terminated in 2020, due to lack of cancer patient participants. There is no clear evidence of anticancer effects in patients so far as clinical trials with such medicines are impossible as they are not permitted for human use.

The Korea Medical Association's National Health Protection Committee said, "In order to use drugs on people, their efficacy and safety must be confirmed through rigorous clinical tests. So far, no clinical trial has been announced to confirm the anti-cancer effect of fenvendazole in humans."

Earlier this year, the National Cancer Center also conducted a clinical trial to confirm the anticancer effect of the animal anthelmintics such as fenbendazole. At the time, researchers at the center reviewed the feasibility of clinical trials by collecting existing research papers based on animal experiments and data cited on various YouTube channels, but finally concluded that there was no proven safety or effect even in the animal testing stage.

An anticancer drug using the mechanism of fenbendazole was first made in the 1990s as a first-generation cytotoxic anticancer drug, and is already used for cancer patients. It is not necessary to use an unproven anthelmintic agent in the situation where even fourth generation anticancer drugs that complement the first generation ones are being developed.

"There are already cytotoxic anticancer drugs with the same mechanism as fenbendazole, so there is no reason to take risks by taking unproven drugs," said Lee Dae-ho, a professor of oncology at Asan Medical Center in Seoul.

Lee also said the discussion on the ingredients of the drug was concluded 20 to 30 years ago.

"It is utterly dangerous to use these drugs on humans. The damage is concerning. Such pseudo-science is being spread by laymen," he said.

Heo Dae-seok, a professor of hemato-oncology at Seoul National University Hospital, said in the Journal of the Korean Medical Society, "Unverified medical information causes confusion rather than helping patients and their families. Objective verification through evidence-based medical research is necessary, and experts will have to make additional efforts to deliver such accurate information to the public."