Abstract
Background: The global burden of advanced-stage cancers remains a significant challenge, particularly in low- and middle-income countries where access to effective therapies is limited. Stage 4 cancers that have undergone extensive prior treatments and lack actionable mutations generally have limited treatment options. With standard chemotherapy, targeted therapies, and immunotherapies, the median overall survival (mOS) typically ranges from 9 to 12 months. Repurposing existing drugs, such as the antiparasitics ivermectin, fenbendazole, and mebendazole, has garnered attention due to anecdotal reports and robust pre-clinical studies suggesting potential anti-cancer effects.
Objective: This article compiles and systematically presents anecdotal case reports and preliminary clinical data on the use of ivermectin and benzimidazoles (fenbendazole and mebendazole) in patients with stage 4 cancers, aiming to provide a foundation for further scientific investigation.
Methods: Case reports were collected from various online sources, including social media platforms (e.g., X/Twitter) and websites, detailing patient experiences with ivermectin and benzimidazoles, often in combination with conventional therapies. Cases are organized by cancer type, with a focus on stage 4 diagnoses, and include reported outcomes such as tumor shrinkage, biomarker reduction, and imaging results.
Results: A total of 300+ case reports across multiple cancer types (breast, brain, bile duct, bladder, cervical, colorectal, esophageal, endometrial, head and neck, kidney, liver, lung, ovarian, pancreatic, prostate, sarcoma, and skin) were compiled. Notable outcomes include significant tumor volume reductions (e.g., up to 99.7% in pancreatic cancer), biomarker decreases (e.g., CA19-9 dropping from 44,960 to 21 in pancreatic cancer), and reports of “cancer-free” status in some cases. A phase I/II clinical trial on ivermectin and balstilimab in metastatic triple-negative breast cancer reported a 37.5% clinical benefit rate.
Conclusion: These anecdotal reports suggest potential anti-cancer effects of ivermectin and benzimidazoles, warranting further investigation through rigorous clinical trials. Patients should consult oncology specialists to integrate these findings into personalized treatment plans, as the evidence remains preliminary.
Keywords: Ivermectin, Fenbendazole, Mebendazole, stage 4 cancer, advanced cancer, case reports, antiparasitic agents, ivermectin, balstilimab, triple-negative breast cancer, clinical trial, off-label use, personalized medicine.
Introduction
Access to effective, cancer-specific therapies remains limited, particularly in low- and middle-income countries where cancer survival rates lag behind those in high-income settings due to inadequate funding and infrastructure (1, 2). This has led to increased interest in repurposing existing drugs as more affordable alternatives. Exploring such options may provide valuable insights and potential solutions for expanding treatment accessibility, warranting further scientific investigation.
The repurposing of antiparasitic drugs such as ivermectin, fenbendazole, and mebendazole for cancer treatment has gained traction through social media and alternative health platforms, particularly for advanced-stage malignancies where conventional options offer limited prognosis.
Stage 4 cancers that have undergone extensive prior treatments and lack actionable mutations generally have limited treatment options. With standard chemotherapy, targeted therapies, and immunotherapies, the median overall survival (mOS) typically ranges from 9 to 11 months. This reflects the aggressive nature and treatment resistance commonly seen in heavily pretreated metastatic disease.
A recent online article from OneDayMD.com aggregates anecdotal testimonials and case reports, primarily sourced from X (formerly Twitter) posts by Dr. William Makis and patient forums, asserting dramatic responses in stage 4 cancers including breast, brain, lung, pancreatic, prostate, and colorectal types. These reports involve high-dose protocols (e.g., ivermectin at 1-2 mg/kg/day, fenbendazole at 222-2000 mg/day per the “Joe Tippens Protocol,” and mebendazole at 400-1500 mg/day), often combined with standard therapies or adjuncts like curcumin, CBD, melatonin, and ketogenic diets.
A balanced literature search reveals preliminary signals in small trials but emphasizes the need for rigorous validation to avoid misleading patients. Recent studies highlight ivermectin’s synergy with immune checkpoint inhibitors in breast cancer models and mebendazole’s combination with docetaxel in prostate cancer, underscoring repurposing potential. (Nature 2021, Nature 2019)
This analysis evaluates the claims against available scientific literature, highlighting mechanisms, evidence gaps, and potential biases. The review underscores the distinction between inspirational anecdotes and evidence-based medicine, incorporating recent comprehensive reviews on drug repurposing that emphasize antiparasitics’ roles in targeting pathways like Wnt/β-catenin and microtubules.
Another important consideration is the difference in urgency between doctors and patients. While it is reasonable to emphasize that more research is needed to confirm the safety and efficacy of treatments, patients facing serious illnesses often cannot afford to wait for definitive answers.
Some cases are heavily pre-treated and are already resistant to standard therapy. This population with a high unmet need, and their success stories provide a strong ethical justification for exploring ivermectin and mebendazole therapeutic combinations.
Their immediate needs and desire for hope can drive them to explore emerging or off-label therapies despite limited data. This underscores the importance of compassionate communication, clear guidance on potential risks, the right to try and ongoing efforts to accelerate high-quality clinical research.
The objective is to document these cases to stimulate hypothesis generation and encourage rigorous clinical research into these repurposed drugs as potential components of combination therapies.
Methods
Data Collection: Case reports were sourced from publicly available platforms, including X/Twitter, Substack, and other websites, as well as peer-reviewed literature where available. Reports were selected based on their documentation of ivermectin and/or benzimidazole use in stage 4 cancer patients, with outcomes such as tumor size reduction, biomarker changes, or imaging results.
Inclusion Criteria: Cases involved patients with stage 4 cancers treated with ivermectin, fenbendazole, or mebendazole, either alone or in combination with conventional therapies (e.g., chemotherapy, immunotherapy).
Data Organization: Cases are presented alphabetically by cancer type, with details on patient demographics, treatment protocols, and outcomes. Where applicable, quantitative data (e.g., tumor size, biomarker levels) are included to provide measurable outcomes.
Ethical Considerations: As this is a compilation of publicly shared anecdotes, no direct patient interaction or ethical approval was required. However, patient anonymity was preserved where possible.
Results
The compilation includes over 300 case reports across 17 cancer types, with selected cases summarised below. Full details are provided in the following supplementary material:
https://www.onedaymd.com/2025/06/ivermectin-fenbendazole-mebendazole-stage-4-cancer.html.
1. Breast Cancer (40 Cases)
Case 29 (2025): A patient with stage 4 breast cancer with spinal metastases reported near-complete resolution of bone metastases and a breast lump reduction from 46x24 mm to 30x10 mm (SUV max from 46 to 2.2) after using ivermectin, fenbendazole, and complementary therapies (e.g., methylene blue, red light therapy).
Case 28 (2025): A 26-year-old UK woman with triple-negative breast cancer and brain metastases showed a 40% reduction in brain tumor size (5 cm to 3 cm) and significant lung metastases shrinkage after 4 weeks of ivermectin, mebendazole, and Trodelvy.
Clinical Trial (ASCO 2025): A phase I/II study (NCT05318469) of ivermectin combined with balstilimab in metastatic triple-negative breast cancer reported a 37.5% clinical benefit rate (95% CI 15.3%-91.7%) in heavily pretreated patients [3].
2. Brain Cancer (110 Cases)
Case Series 1 - 95 (METRICS study)
The Care Oncology Clinic in the UK, which is now doing clinical trials on glioblastoma, published their preliminary retrospective data from the METRICS study (NCT02201381) in Frontiers in Pharmacology (2019) about the combination standard treatment and repurposed drugs in 95 patients.
Full inclusion and exclusion criteria and further methodological details can be found at https://clinicaltrials.gov/ct2/show/NCT02201381:
Subjects will take the following treatments (adjunctive) and have their data collected from their medical records every 3 months.
Oral Mebendazole 100 mg once a day, for study duration.
Oral atorvastatin up to 80 mg once a day, for study duration.
Oral metformin up to 1000 mg once a day, increased to bid if tolerated after 2 weeks, for study duration.
Oral doxycycline 100 mg once a day, for study duration.
The retrospective analysis consisted of 95 patients with advanced GBM (brain cancer) grade IV (Glioblastoma Multiforme) who attended the clinic between 2013 and 2016. Simply adding metformin, doxycycline, atorvastatin, and mebendazole in addition to optimal standard of care can increase GBM (Glioblastoma) average survival from 15 to 27 months, almost a doubling.
Note: Although the fenbendazole and mebendazole are very similar in effectiveness at higher doses, Mebendazole has superior brain cancer cell killing at lower doses compared to Fenbendazole. So for Glioblastoma, it’s Mebendazole if you can get it.
Read More: Ivermectin and Mebendazole for Brain Cancer Success Stories: 112 Case Reports (2025)
3. Bile Duct Cancer (Cholangiocarcinoma) (1 Case)
Case 1 (2024): A 53-year-old Canadian patient with stage 4 cholangiocarcinoma (15 cm tumor) achieved “cancer-free” status after 14 months of fenbendazole (444 mg/day), ivermectin (2.5 mg/kg/day), and CBD-THC oil, following initial chemotherapy failure.
4. Cervical Cancer (1 Case)
Case 1 (2024): A woman in her 50s with stage 4 cervical cancer and liver metastases achieved a 46% CA125 reduction (99.1 to 53.6 U/mL) after 1.5 months of high-dose ivermectin (2 mg/kg/day) and fenbendazole (2000 mg/day), with brand switching noted as critical for efficacy.
5. Colorectal Cancer (36 Cases)
Case 23 (2025): A 59-year-old Canadian woman with stage 4 colon cancer (liver and lymph node metastases) reported a 20% aggregate tumor size reduction after 1.5 months of ivermectin (1.5 mg/kg/day), fenbendazole (1500 mg/day), and CBD oil.
Case 22 (2025): A 61-year-old man with stage 4 appendix cancer achieved a 68% tumor volume reduction after 2 months of ivermectin (1.5 mg/kg/day), mebendazole (1500 mg/day), and chemotherapy/immunotherapy.
Read More: Ivermectin, Fenbendazole and Mebendazole for Stage 4 ColoRectal Cancer: 36 Case Reports Compilation (2025)
6. Esophageal and Stomach Cancer (5 Cases)
Case 4 (2025): A 55-year-old patient with stage 4 gastric cancer and bone metastases achieved a 99% reduction in CA19-9 and CEA markers after using ivermectin and fenbendazole.
Case 3 (2023): A 66-year-old man with stage 4 esophageal adenocarcinoma (18 cm tumor, lung and lymph node metastases) achieved “no evidence of disease” after 14 months of fenbendazole (222 mg/day) and complementary supplements.
7. Endometrial (Uterine) Cancer (6 Cases)
Case 1 (2023): An 81-year-old woman with recurrent stage 4 endometrial cancer (abdominal, lymph node, and lung metastases) showed significant tumor shrinkage and resolution of ascites after 5 months of fenbendazole and complementary therapies (e.g., high-dose melatonin, turmeric).
8. Head and Neck Cancer (5 Cases)
Case 5 (2025): A 67-year-old woman from Zimbabwe with stage 4 oropharyngeal squamous cell carcinoma achieved a 46%-93% tumor volume reduction in liver, pelvic lymph nodes, and bone metastases after less than 3 months of ivermectin (1 mg/kg/day) and mebendazole (1000 mg/day).
9. Kidney and Urinary Bladder Cancer (13 Cases)
Case 7 (2025): A 63-year-old man with stage 4 clear cell renal cell carcinoma achieved “cancer-free” status after 3 months of ivermectin (1-2 mg/kg/day) and fenbendazole (1000 mg/day), with no evidence of recurrence on PET/CT.
Case 1 (2025): A 75-year-old man with stage 4 urothelial bladder cancer with multi-organ metastases showed dramatic PET/CT improvements after combining fenbendazole (222-1500 mg/day) and ivermectin (30 mg/day to 1 mg/kg/day) with Padcev and Keytruda.
10. Liver Cancer (1 Case)
Case 1 (2021): A patient with stage 4 hepatocellular carcinoma reported improved outcomes after fenbendazole, despite no improvement with radiation and immunotherapy.
11. Lung Cancer (20 Cases)
Case 18 (2025): A 67-year-old New York woman with stage 4 non-small cell lung cancer (NSCLC) showed resolution of lymph node, adrenal, and renal metastases and healing of bone metastases after 5 months of ivermectin (1 mg/kg/day), fenbendazole (888 mg/day), and CBD oil.
Read More: Ivermectin, Fenbendazole and Mebendazole for Lung Cancer: 36 Case Reports Compilation (2025)
12. Ovarian Cancer (8 Stage 4 Cases)
Case 10 (2025): 79 year old woman in France with Stage 4 Ovarian Cancer achieved complete metabolic regression in 2 months.
Case 4 (2025): A 67-year-old woman with stage 4 ovarian cancer achieved a CA125 reduction from >7000 to 27 and no metastases on PET/CT after 2 months of ivermectin (1.5 mg/kg/day), fenbendazole (1500 mg/day), and chemotherapy.
Full case report details are provided in the following supplementary material:
Ivermectin, Fenbendazole and Mebendazole for Stage 4 Ovarian Cancer: 8 Case Reports Compilation
13. Pancreatic Cancer (30 Cases)
Case 16 (2025): A Canadian patient with stage 4 pancreatic cancer, offered euthanasia, achieved “undetectable” cancer on CT after fenbendazole (444 mg/day) and ivermectin (50 mg/day) for 5 months.
Case 7 (2025): A 77-year-old patient with stage 4 neuroendocrine pancreatic cancer achieved a 99.9% CA19-9 reduction (44,960 to 21) and 70%-87% tumor shrinkage with mebendazole (1000 mg/day) and fenbendazole (888 mg/day).
Full case report details are provided in the following supplementary material:
Ivermectin, Fenbendazole and Mebendazole for Stage 4 Pancreatic Cancer: 30 Case Reports Compilation
14. Prostate Cancer (40 Cases)
Case 17 (2025): A 77-year-old man with stage 4 prostate cancer (lung and bone metastases) achieved near-complete resolution on PET/CT after 5 months of ivermectin (1.5 mg/kg/day), fenbendazole (888 mg/day), and CBD oil.
Full case report details are provided in the following supplementary material:
Ivermectin, Fenbendazole, and Mebendazole for Stage 4 Prostate Cancer: 40 Case Reports Compilation
15. Sarcoma (2 Cases)
Case 2 (2025): A patient with stage 4 leiomyosarcoma reported tumor growth cessation and no further need for blood transfusions after 1 month of mebendazole and ivermectin.
16. Skin Cancer (4 Cases)
Case 4 (2025): An Australian man with stage 4 malignant melanoma achieved “cancer-free” status after 12 months of ivermectin and fenbendazole.
Discussion
The compiled case reports suggest potential anti-cancer effects of ivermectin and benzimidazoles (fenbendazole or mebendazole), often in combination with conventional therapies. Reported mechanisms include inhibition of the WNT-TCF pathway [4], induction of apoptosis, and chemosensitization/radiosensitization [5, 6].
Notable outcomes include significant tumor volume reductions (e.g., 99.7% in pancreatic cancer), biomarker decreases (e.g., PSA from 2093 to 39 in prostate cancer), and improved quality of life.
Public median survival for stage 4 pancreatic is around 3–6 months post-diagnosis vs. multiple cases reporting survival beyond 1 year with fenbendazole and ivermectin in this case series.
It is important to note that many of these stage 4 cancer case reports involve patients who have failed chemotherapy and yet achieved complete response rates (no evidence of disease, NED). Such outcomes are rare. Mechanistic studies show that antiparasitic agents like ivermectin, fenbendazole, and related drugs can target multiple cancer hallmarks, including overcoming drug resistance and inhibiting cancer stem cells. Caution is warranted, and more rigorous studies are needed to establish their safety and efficacy in cancer treatment.
The phase I/II trial on ivermectin and balstilimab [3] provides preliminary clinical evidence, but larger, randomized controlled trials are needed to establish efficacy and safety. Differences in response rates (e.g., variable efficacy in prostate cancer) and optimal dosing (e.g., higher doses of ivermectin at 1-2 mg/kg/day vs. lower doses in some cases) highlight the need for standardized protocols.
Limitations: The anecdotal nature of these reports limits their generalizability. Lack of control groups, variable treatment protocols, and potential confounding from concurrent therapies (e.g., chemotherapy, immunotherapy) complicate attribution of outcomes to ivermectin or benzimidazoles. Furthermore, social media sources are not indexed in scientific databases, increasing the risk of misinformation.
Conclusion
This compilation of anecdotal case reports provides preliminary evidence of the potential anti-cancer effects of ivermectin and benzimidazoles (fenbendazole or mebendazole) in stage 4 cancers. This comprehensive compilation of advanced cancer case reports and preliminary clinical trial data highlights a growing interest in repurposing anti-parasitic agents for oncology. While ivermectin and fenbendazole are not established universal cures, their safety profiles and observed anecdotal responses justify further clinical investigation (9, 10).
For example, case reports and small clinical studies with mebendazole have documented tumor regression or disease stability in individual patients with metastatic cancers, and phase I trials have shown that high-dose mebendazole can be administered safely in combination with standard treatments (11). Fenbendazole has demonstrated anti-cancer effects in laboratory studies and some animal models. Ivermectin has shown anti-tumor effects in preclinical studies and is being evaluated in early-phase clinical trials.
With their low cost and accessibility, ivermectin and benzimidazoles represent promising candidates for further investigation—either as standalone treatments or in combination with traditional therapies—for patients with advanced cancers. This work seeks to encourage additional research into repurposed drugs as part of a comprehensive multimodal approach to cancer care.
These testimonials could represent just the tip of the iceberg—an emerging frontier that science is only beginning to explore. For a more comprehensive understanding, it’s worth looking into additional research studies and clinical trials. As always, consult with your healthcare provider(s) before making any treatment decisions, as close monitoring and personalised care are essential.
Acknowledgments
The authors acknowledge the contributions of patients and advocates who shared their experiences on public platforms, as well as researchers like Dr. William Makis for their efforts in documenting these cases.
References:
https://www.weforum.org/stories/2024/03/global-cancer-funding-shortfall/
https://www.who.int/news/item/01-02-2024-global-cancer-burden-growing--amidst-mounting-need-for-services
Yuan Y, et al. Phase I/II study of ivermectin and balstilimab in metastatic triple-negative breast cancer. J Clin Oncol. 2025;Abstract e13146.
Melotti A, et al. The river blindness drug ivermectin and related macrocyclic lactones inhibit WNT-TCF pathway responses in human cancer. EMBO Mol Med. 2014;6(10):1263-1278.
Mudassar F, et al. Targeting tumor hypoxia and mitochondrial metabolism with anti-parasitic drugs to improve radiation response in high-grade gliomas. J Neurooncol. 2020;147(2):393-403.
Zhang L, et al. Mebendazole potentiates radiation therapy in triple-negative breast cancer. Int J Radiat Oncol Biol Phys. 2019;103(1):195-207.
Survival and chemotherapy success rates for various cancers https://www.medicalnewstoday.com/articles/326031
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2794946
https://ar.iiarjournals.org/content/44/9/3725
https://pmc.ncbi.nlm.nih.gov/articles/PMC7505114/
https://pmc.ncbi.nlm.nih.gov/articles/PMC9862092/
https://www.onedaymd.com/2025/06/ivermectin-fenbendazole-mebendazole-stage-4-cancer.html.
Fenbendazole and Ivermectin for Cancer: Real Stories, Science & Protocols (2026 Guide)
Disclaimer: Patients should consult with oncology specialists before considering any alternative or adjunctive therapies. The information presented here is for research and informational purposes only and does not constitute medical advice.
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