Articles and TikTok videos have gained traction in social media that claim a dog deworming drug, fenbendazole (also known as Panacur), cures cancer. The claims are based on anecdotal accounts of a man who had lung cancer and pursued treatment with fenbendazole, which is sold as a parasiticide in animal health clinics. He said his tumors went into remission and he became cancer-free, but he didn’t have any other conventional therapies or a control group to compare his results against. The evidence supporting fenbendazole as an effective cancer therapy is sparse and unconvincing.

Fenbendazole interferes with the formation of microtubules, which are a protein scaffolding that establishes shape and structure for cells. Textbook depictions of cells often portray them as floating in amorphous bags of liquid, but they establish their shape and structures through a complex protein network called the cytoskeleton. Microtubules are the major components of the cytoskeleton, and they are made of a protein called tubulin.

Inhibition of tubulin polymerization by fenbendazole inhibits cell-cycle progression and may induce mitotic catastrophe. To test this, A549 human cancer cells were synchronized with serum starvation for 48 h and treated with 1 uM fenbendazole for different time intervals. Cells were then irradiated at 10 Gy in aerobic or hypoxic conditions. Time to four-fold tumor volume was measured for each treatment group. Treatment with fenbendazole did not alter the growth of either the unirradiated or irradiated tumors. (Table I)

Fenbendazole has not been proven to prevent cancer in humans, and it may even cause a variety of side effects in some patients. We should be cautious about recommending it for cancer treatment, and physicians should consider patients’ anecdotal reports and other sources of information when discussing a potential treatment regimen.fenbendazole for cancer