Fenben, also known as Pancur or Safe-Guard, is a medication used to treat parasites and worms (roundworms, hookworms, whipworms, lungworms and some tapeworms) in animals. It is a broad-spectrum anthelmintic compound belonging to the benzimidazole family of antiparasitic agents and is commonly sold in pet stores under its veterinary brand name. More recently, fenben has been claimed by cancer patients as an effective treatment in combination with radiation for metastatic lung cancer.

In a case report, a patient with advanced non-small cell lung cancer self-administered fenbendazole and experienced tumor shrinkage (Table I). A previous study showed that when human adenocarcinoma cells expressing KRAS mutations were transplanted into athymic nu/nu mice and treated with 1 mg/mouse of fenbendazole, there was a significant reduction in tumor size and weight, suggesting that fenbendazole has in vitro and in vivo antitumor effects in animal models.

We conducted a focus group interview with 21 lung cancer patients who reported taking fenbendazole to treat their tumors, using a semi-structured questionnaire divided into three categories: 1) the channels through which they acquire general cancer information and false information; 2) the quality of obtained information; and 3) their perception and attitude toward the information.

We also studied the effect of fenbendazole on the radiation response of EMT6 carcinoma cells. These cells were randomized to serve as unirradiated controls or receive either three i.p. injections of fenbendazole or 10 Gy of irradiation. The accumulation of the radiosensitizer rhodamine 123 was assessed in both unirradiated and irradiated cultures as a measure of P-gp efflux. We found that fenbendazole does not affect the radiation dose-response curve of EMT6 cells, either in aerobic or hypoxic conditions.