OP, what type of cancer? I'm engaged with MDA for melanoma. According to my MDA medical team (and CGPT Deep Research) there are no clinical trails proving or disproving ivermectin to be effective for skin cancers. That could be due to the lack of pharma incentives to clinically test this. Some people are reportedly using Ivermectin 1.87% "horse paste" topically to supplement other conventional treatments.
One thing you may not have considered is Vitamin B3. There reportedly HAVE been clinical tests showing reduction in "non-melanoma skin cancers". My MDA oncologist indicated there haven't been tests for B3 and melanoma, but said "it can't hurt and could help". Below is from CGPT DR on B3 and skin cancer.
1. Nicotinamide (Vitamin B3) Oral Supplement
Dosage: 500 mg twice daily
Evidence: A major clinical trial (ONTRAC study, NEJM 2015) found that nicotinamide reduced the rate of new non-melanoma skin cancers by ~23% in high-risk patients.
Mechanism: Helps repair DNA damage from UV exposure and enhances skin immune function.
Safety: Very well tolerated. Unlike niacin, it does not cause flushing.
Recommended for: People with sun damage, prior skin cancers, or actinic keratoses.