Some studies have shown that antiparasitic drugs can slow cancer cell growth in cells and animals. However, there isn’t enough evidence from randomized clinical trials to show that the drug fenbendazole cures cancer in humans.
Fenbendazole is an anthelmintic, a drug that kills parasitic worms. It’s used to treat gastrointestinal parasites, but has also been studied for its possible use in treating other types of tumors and as an adjunct therapy to traditional cancer therapies such as radiation and chemotherapy.
A 2020 report from Seoul National University researchers stated that fenbendazole “showed clear anti-tumor effects in both animal models and human subjects, including improved survival time.” However, the authors acknowledge that further research is required before fenbendazole can be considered for use in humans. Moreover, Health Canada lists fenbendazole as a veterinary drug for dogs and cats only, not for human use.
The nonprofit organization Cancer Research UK told PolitiFact that while Tippens’ anecdotal experience is interesting, there is insufficient evidence that fenbendazole cures or treats cancer. The U.S. Food and Drug Administration has also told PolitiFact that the drug isn’t approved or available for the treatment of cancer.
As with other anecdotal reports, there may be other factors in Tippens’ remission beyond fenbendazole, such as conventional cancer treatments he received, that aren’t being accounted for. And, because he wasn’t part of a control group taking a placebo, it isn’t possible to reliably attribute his improvement to fenbendazole alone.
Three daily 50 mg/kg/day fenbendazole injections didn’t affect the growth of unirradiated EMT6 tumors in BALB/c mice, or the time it took for these tumors to reach four-times their initial volume when they were first stratified for treatment. Similarly, when EMT6 tumors were treated with fenbendazole in their diet or injected as described above and then exposed to 10 Gy of local x-ray radiation, there was no effect on either the growth of these tumors or the time it took for them to reach a four-fold increase in their volume.
However, a number of experiments have shown that fenbendazole enhances the cytotoxicity of radiation and the anticancer drug docetaxel in cancer cells. In these experiments, cells were made hypoxic by sealing their culture bottles with rubber gaskets that have needles for influx and efflux of gases and then gassing them with a mixture of 95% nitrogen/5% carbon dioxide containing 1 ppm oxygen before adding a 2-h treatment with increasing doses of docetaxel or fenbendazole. The relative surviving fractions of cultures treated in hypoxia were significantly higher than those of controls. The same results were observed when cultures were treated in air. Hypoxia significantly increased the sensitivity of the cells to fenbendazole compared to those in non-hypoxic conditions. fenbendazole for cancer