A humble deworming pill, familiar to millions of Kenyans, is at the centre of a global scientific storm, sparking both immense hope and serious debate. Researchers are investigating whether this cheap, widely available medication could be repurposed into a powerful weapon against cancer, potentially offering a lifeline for patients who have exhausted conventional treatments.

The core of this excitement lies in a class of drugs called benzimidazoles—specifically mebendazole and its veterinary counterpart, fenbendazole. These drugs, used for decades to treat parasitic worms, are now showing an unexpected ability to attack cancer cells in laboratory settings. [1, 5] This has ignited a wave of interest in "drug repurposing," a strategy to find new uses for older, approved medicines, which could dramatically cut the cost and time needed to develop new cancer therapies. [2, 4]

How a Dewormer Fights Cancer

Early research suggests these dewormers combat cancer in several ways. They appear to disrupt the formation of tiny internal structures in cancer cells called microtubules, which are vital for cell division—a mechanism similar to some chemotherapy drugs. [5, 7] Furthermore, studies indicate they can starve tumours by interfering with their ability to absorb glucose, a key source of energy for their rapid growth. [1, 6] This multi-pronged attack has shown effectiveness against various cancer cell lines in labs, including those resistant to standard treatments. [1, 7]

Scientists at Johns Hopkins University have even developed a new, more potent crystal form of mebendazole, dubbed 'polymorph C', which they believe is more effective at penetrating and fighting tumours. [3, 9] In Kenya, a standard 500-milligram tablet of mebendazole is readily available over-the-counter, typically costing between KES 1,175 and KES 1,305. [9] The prospect of a widely accessible and affordable cancer treatment is a tantalizing one, particularly in a country where the cost of oncology care places a heavy burden on families.

A Word of Caution

Despite the promising lab results and a surge of anecdotal success stories online, medical experts are urging extreme caution. [10] Much of the excitement around fenbendazole, for example, is fuelled by personal testimonials from patients who were often simultaneously undergoing conventional treatments like immunotherapy, making it impossible to credit the dewormer alone for their recovery. [10, 17] The American Cancer Society has warned that these stories, while compelling, do not constitute scientific proof. [10]

Crucially, fenbendazole is not approved for human use, and there is a significant lack of rigorous clinical trials to determine its safety and effectiveness in people. [10, 11] Researchers note that a major challenge is the drug's poor solubility, which may prevent it from reaching tumours in high enough concentrations to be effective when taken orally. [1, 15]

• Evidence Gap: Most studies are preclinical (in labs or animals) and may not translate to humans. [11]
• Safety Concerns: Self-medicating carries risks, with some reports linking the drug to liver injury. [15]
• The Need for Trials: Scientists emphasize that only well-designed human clinical trials can truly validate if these drugs are safe and effective for cancer patients. [1, 11]

While the prospect of turning a simple dewormer into a cancer-fighting agent is a significant development, the journey from the laboratory to the clinic is a long and cautious one. For now, it remains a story of immense potential that must be tempered with scientific rigour and patience.