The news that caught the attention of Korean cancer patients in recent months was not about new anticancer drug development but about “animal anthelmintics.” A YouTube video of a U.S. patient diagnosed with small cell lung cancer claimed he had been cured by fenbendazole (animal anthelmintic) while attending a clinical trial with other anticancer drugs at the MD Anderson Cancer Center. When fenbendazole became difficult to obtain on the market, even the human anthelmintic (albendazole) sold out.

Anticancer effects of anthelmintics
The anticancer effects of fenbendazole, albendazole, and mebendazole have been known against cancer cell lines in vitro for a long time. Microtubule destabilization is suggested as a mechanism of action. Based on these findings, clinical trials have been conducted on cancer patients with albendazole or mebendazole. One Swedish clinical trial was initiated on Aug. 11, 2018, and terminated on Jan. 22, 2020, due to lack of effect after enrollment of 11 cancer patients. There is no definite evidence of anticancer effects in patients so far. A clinical trial with fenbendazole is impossible because it is not permitted for human use due to toxicities.

Safety issues
The U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) prohibit fenbendazole for human use. The recommended dosage for an animal is 5 mg/kg, which is more than 100 times of acceptable daily intake for human safety (40 micrograms per kilogram body weight). The decision was based on toxicity and teratogenicity studies conducted in Hoechst Research Laboratories (NADA 128-620). Actual toxicities, such as acute hepatitis, following self-administration of fenbendazole, are reported.

Social reactions
Even though the Ministry of Food and Drug Safety warned that this claim was unfounded and that the side effects of such drugs could damage patients, the frenzy for the anthelmintics is still ongoing. A conspiracy theory argues that pharmaceutical companies are interfering with clinical trials of anthelmintics in cancer patients. However, it is not true because several clinical trials have been made with support from companies (clinicaltrials.com).

Claims to cure terminal cancer patients with untested new drugs or food supplements have appeared repeatedly under the media spotlight and disappeared later. The desperation of terminal cancer patients and their families is fully understood emotionally, clinging to such claims like people clutching at straws if there is a slight possibility.

Greek philosopher, Jamblichus, wrote 2,000 years ago: “Medicine is the daughter of dreams.” This message still resonates today. When faced with a bleak or uncertain reality, we tend to pursue "dreams” or hope. However, rather than questioning whether our dreams are valid, we naively cling to the presence of dreams. Such dreams inevitably become stronger than rational thought.

In the internet environment, where anyone can have easy access to various untested medical data, information is delivered without filtration, and the propagation speed is surprisingly fast. Claims are not always facts. Unverified medical information is causing confusion or unnecessary pain rather than helping patients and their families.

To minimize such unnecessary confusion, objective verification through evidence-based medicine is required. Additional efforts of experts are needed to disseminate validated medical information to the public (especially patients).

This article was originally published in the Journal of Korean Medical Science.—Ed.