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My Exploration of Fenbendazole: A Research Journey into an Unlikely Compound

Last Updated: November 13, 2025

When I first came across the name fenbendazole, I knew it only as a veterinary antiparasitic drug — something used to treat intestinal worms in animals. But as I began diving into the growing body of research and personal stories circulating online, I became genuinely curious. Could this inexpensive benzimidazole compound really have properties worth exploring in cancer research?

What Drew Me In

The science behind fenbendazole (FBZ) fascinated me. It belongs to the same family of compounds that affect microtubule formation — the structural framework of cells. In laboratory studies, FBZ has been shown to disrupt microtubule polymerization, induce apoptosis, and even influence glucose metabolism in certain cell lines.

I started reading every paper I could find. The more I read, the clearer it became that while preclinical studies are promising, there’s still a massive gap between animal data and human evidence. Clinical research is limited, and most of what’s available comes from anecdotal case reports or self-administered experiences.

The Case Series That Caught My Attention

One study in particular — “Fenbendazole as an Anticancer Agent? A Case Series of Self-Administration in Three Patients” by Makis, Baghli, and Martinez (link) — made a strong impression on me. It described three individuals with advanced cancers (breast, prostate, and melanoma) who decided, on their own, to include fenbendazole in their routines.

Overview of the Case Series

The publication by Makis et al. describes three patients diagnosed with advanced or metastatic cancers (breast, prostate, and melanoma). Each patient independently chose to add fenbendazole to their ongoing treatment plan, typically alongside other therapies such as hormonal therapy, immunotherapy, or radiation.

Across follow-up periods ranging from 11 months to nearly three years, the individuals reported no adverse effects related to fenbendazole and experienced varying degrees of disease remission. It is crucial to note that these observations are anecdotal and occurred outside a controlled clinical trial. Therefore, no conclusions can be drawn about fenbendazole’s role in these outcomes.

Case Summaries

• Case 1 (Breast Cancer) – An 83-year-old woman with recurrent metastatic breast cancer began self-administering 222 mg/day of fenbendazole, along with hormone-blocking medication. Over eight months, her imaging and tumor markers normalized, and she remained disease-free during follow-up.

• Case 2 (Prostate Cancer) – A 75-year-old man with recurrent stage IV prostate cancer and bone metastases introduced fenbendazole (222–444 mg/day) alongside androgen deprivation therapy and supplements. Over a two-year period, imaging showed regression of metastatic lesions, and PSA levels stayed undetectable.

• Case 3 (Melanoma) – A 63-year-old man with BRAFV600-mutated melanoma and recurrent disease self-administered fenbendazole (222–444 mg/day) for several weeks before receiving immunotherapy. His tumor markers rapidly decreased, and he maintained “no evidence of disease” for 11 months post-treatment.

All three individuals initiated fenbendazole independently, motivated by reports of potential anticancer properties circulating in public forums. Physicians were informed in some cases, but no official prescriptions were issued.

My Takeaway

This case series adds to the small but growing body of literature examining fenbendazole in the context of oncology research. While intriguing, these patient experiences remain observational and hypothesis-generating, not confirmatory.

Fenbendazole’s mechanisms of action — particularly its effects on microtubule dynamics, metabolism, and apoptosis — continue to attract attention in preclinical models. The next step for the scientific community lies in rigorous, controlled human studies that can clarify whether fenbendazole has any measurable clinical benefit and establish appropriate safety parameters.

Until such data are available, fenbendazole should be viewed strictly as a subject of research interest, not as a proven or approved therapy for cancer or any other human disease.

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Keywords: Fenbendazole, Veterinary Antiparasitic, Benzimidazole, Drug Repurposing, Case Series, Cancer Research, Oncology, Self-Administration

"All opinions and statements expressed in this blog are those of the author alone and do not represent the official position of RT Labs."