@davyjohn, I moved your question about alternative approaches to the original discussion that you started about your son's choices and living with stage 4 pancreatic cancer.

Fenbendazole and ivermectin are an antiparasitic drug used in veterinary medicine to treat animal gastrointestinal parasites. There are many stories circulating on social media about using it to treat cancer because preliminary research is investigating their use in cancer.

The use of fenbendazole for cancer is still experimental (in mice), and more studies are needed to determine its success and safety in humans.

Untested treatments can do harm. When we read repeated stories of success about this or other unproven treatments that circulate widely, the repetition can give the appearance of - it must be true or everyone is doing it.

As @stageivsurvivor said in another discussion here https://connect.mayoclinic.org/comment/1186515/:
“Think carefully as drug/drug and drug/supplement interactions can have consequences. Damage to the liver would mean having to pause chemo. Permanent damage would terminate cancer treatment. Bad decisions can have bad consequences and there might not be a “do-over” moment.”

Always seek the advice of your physician or other qualified health provider with any questions you may have regarding your health. Never disregard professional medical advice or delay in seeking it because of something you have read on the community or on social media.

Please be careful about advice from the internet echo chamber.
https://www.anticancerfund.org/en/blog/separating-fact-fiction-repurposed-drugs-cancer-treatment