Is ivermectin effective for treating breast cancer?

Ivermectin Should NOT Be Used for Breast Cancer Treatment

Ivermectin has no proven therapeutic utility for breast cancer and is not approved by the FDA for any cancer indication—patients should pursue evidence-based cancer therapies instead. 1

Regulatory Status and Clinical Evidence Gap

• The FDA approves ivermectin exclusively for specific parasitic infections, with no authorization for cancer treatment of any kind. 1
• Despite promising preclinical laboratory studies, there are no large-scale randomized controlled trials in humans demonstrating therapeutic benefits for breast cancer. 2
• A critical translational gap exists between laboratory findings and actual clinical application—what works in cell cultures and animal models has not been validated in breast cancer patients. 2

Why the Laboratory Data Cannot Guide Clinical Practice

While preclinical studies show interesting mechanisms (inhibition of PAK1/Akt signaling pathways, induction of autophagy, and potential synergy with immunotherapy in mouse models), these findings remain confined to the laboratory:

• In vitro studies demonstrated ivermectin can inhibit breast cancer cell proliferation through cytostatic autophagy by blocking the PAK1/Akt/mTOR pathway. 3, 4
• Animal studies showed potential synergy with checkpoint inhibitors like anti-PD1 antibody in mouse breast cancer models. 5
• Recent laboratory work suggests combination strategies with methionine-depleting agents may enhance efficacy. 6

However, none of these laboratory observations have been translated into proven human benefit, and laboratory efficacy does not predict clinical success.

Significant Safety Concerns

• Higher doses of ivermectin—potentially required for any theoretical anticancer effect—may cause significant adverse effects beyond those seen with standard antiparasitic dosing. 1
• At approved doses for parasitic infections, ivermectin can cause dizziness, nausea, fever, headache, muscle/joint pain, and skin reactions. 7
• Patients with severe liver disease face increased toxicity risk. 8, 7
• Moderate certainty evidence from COVID-19 studies suggests potential for serious adverse events at higher doses (RR 3.10,95% CI 0.54-17.89). 7

The Real Clinical Danger: Treatment Delay

The most serious risk is that patients may delay or forgo proven breast cancer therapies while pursuing ivermectin:

• Social media misinformation promotes ivermectin's unproven cancer benefits, leading to self-medication and documented cases of toxicity in oncology patients. 2
• The drug's low cost and accessibility make it particularly appealing in resource-limited settings, creating ethical challenges when patients abandon evidence-based treatments. 1, 2

What Patients Should Receive Instead

Standard evidence-based breast cancer treatment includes:

• Chemotherapy: Anthracycline-containing polychemotherapy regimens (with doxorubicin, epirubicin, 5-FU, cyclophosphamide) improve progression-free survival and overall survival in node-positive breast cancer. 9
• Hormone therapy: Tamoxifen for 5 years at 20 mg daily is beneficial for estrogen receptor-positive tumors regardless of age. 9
• Radiation therapy: Indicated based on lymph node involvement and tumor location. 9
• Surgical management: Appropriate breast-conserving surgery or mastectomy with axillary assessment. 9

Communication Strategy with Patients

Healthcare providers must directly address ivermectin inquiries by:

• Clearly stating the absence of human clinical evidence for cancer treatment. 2
• Explaining that laboratory studies do not translate to clinical recommendations. 2
• Emphasizing the proven efficacy of standard breast cancer therapies. 9
• Warning against treatment delays that could worsen outcomes and reduce quality of life. 2