Drug repurposing has become an area of interest in cancer research because it examines whether existing medicines may have additional uses beyond their original purpose.

A recent prospective observational cohort evaluated real-world outcomes among cancer patients who were prescribed a combination of ivermectin and mebendazole through a telemedicine platform. Both drugs are primarily known as antiparasitic agents, but the paper describes preclinical research suggesting possible anticancer mechanisms, including effects on cancer cell proliferation, cancer stem cells, microtubules and several signaling pathways.

The study included 197 adult cancer patients at baseline. Of those, 122 completed a follow-up survey approximately six months later. The participants represented a range of cancer types, including prostate, breast, lung, colon, liver and other malignancies. The mean age was 67 years, and the group included both men and women in nearly even proportions.

At enrollment, 37.1 percent of participants reported that their cancer was actively spreading or progressing. Many participants had also received conventional cancer treatments, including surgery, chemotherapy, radiation therapy, immunotherapy, hormone therapy and targeted therapy.

Participants received compounded oral capsules containing 25 mg ivermectin and 250 mg mebendazole. The initial prescription generally included 90 capsules. Dosing schedules were individualized by the prescribing provider and patient, with one or two capsules per day among the most common patterns.

At six-month follow-up, 86.9 percent of respondents reported completing the full initial 90-capsule prescription, and 66.4 percent reported that they were still taking the protocol. Side effects were reported by 25.4 percent of follow-up participants. The most common side effects were gastrointestinal symptoms, fatigue or weakness, dizziness, skin reactions, neurological symptoms, headache, loss of appetite and muscle or joint aches. Among those who reported side effects, most continued treatment either without changing the regimen or after temporarily reducing or pausing it.

The paper reports several self-reported cancer outcomes at six months. No current evidence of disease was reported by 32.8 percent of follow-up respondents. Tumor regression was reported by 15.6 percent. Stable disease was reported by 36.1 percent. Progression was reported by 15.6 percent.

Using the paper’s definition, the clinical benefit ratio included participants reporting no current evidence of disease, regression or stable disease. That ratio was 84.4 percent among the follow-up respondents. The combined group reporting no current evidence of disease or regression was 48.4 percent.

The study also examined dose levels. The authors reported no significant dose-response association for cancer outcomes across the one-to-four-capsule dosing groups. They did report a significant association between dose level and side effects, with the highest side-effect rate observed in the two-capsule group.

The paper also notes that participants often used other interventions at the same time. At follow-up, some participants reported chemotherapy, radiation therapy or surgery. Others reported supplements, dietary changes, fasting, ketogenic or low-sugar diets, hyperbaric oxygen, red-light therapy and other approaches.

Because of that, the study cannot determine whether the reported outcomes were caused by ivermectin and mebendazole. The authors identify several limitations: the observational design, reliance on self-reported outcomes, lack of a control group, lack of radiographic confirmation and the possibility of confounding from conventional therapies, supplements and lifestyle changes.

The authors describe the findings as hypothesis-generating. They call for rigorous randomized, double-blind, placebo-controlled trials to evaluate safety, efficacy, dosing and the role of the combination across specific cancer types.

The study adds to a broader discussion about whether repurposed, lower-cost medicines should be examined in oncology through more formal clinical research. According to the paper, standard chemotherapy costs can average far more annually than an ivermectin-mebendazole regimen, though cost comparisons do not establish treatment effectiveness.

The central question raised by the paper is not whether the findings are final. The central question is whether the reported signal should be tested under stronger clinical conditions.

A controlled trial would allow researchers to compare outcomes against a defined control group, verify cancer status through clinical records and imaging, separate results by cancer type and stage, monitor safety more closely and evaluate whether the combination provides benefit on its own or only alongside other treatments.

Until that type of research is completed, the study remains a real-world observational report with notable self-reported outcomes and important limitations.

Its next step is not conclusion.

Its next step is verification.