Fenbendazole (FZ) is an anthelmintic compound belonging to the benzimidazole family of drugs. It is widely used in veterinary medicine to treat parasitic infections, including gastrointestinal nematodes and lungworms. It is also reported to have antitumor effects in animal models and human cancer cells.  In one study, fenbendazole significantly inhibited the growth of human colon adenocarcinoma xenografts when administered orally to mice in vivo and suppressed cellular clonogenicity and tumorigenesis of KRAS mutant human lung adenocarcinomas grown as xenografts in athymic BALB/c mice by causing microtubule interferance and modulating several key cellular pathways, including RAS signaling.
A patient with advanced non-small cell lung cancer (NSCLC) self-administered fenben dazole after watching videos of a veterinarian who claimed that the dog deworming medicine had cured her of her cancer. This case report highlights the importance of physicians inquiring about patients’ self-administration of orally ingested products such as dietary supplements and herbs, especially when they claim to have therapeutic effects. Furthermore, it illustrates that online social media can be a useful source of information on alternative therapies for cancer but should only be used in conjunction with medical advice.