[godsfshrmn]

Gold standard we use in oncology are the National comprehensive Cancer Network - https://nccn.org There are guidelines for almost all malignancies and their standard methods of treatment. They are very detailed. They outline (many flowcharts) what to do on the second, third and sometimes 4th recurrence of malignancy.

You need to register for an account to view them, but it is still free I believe. You'll find out more than you would want to know there

[refurb]

I worked in the biotech space and this - NCCN (US) or ESMO (EU) guidelines are the place to start. Unless you're a very unique case, most doctors won't even consider cutting edge therapies until you've failed at least one of the more common treatments.

Sign up for a free account and download the guidelines. They are evidence driven and give you a sense of what the current standard of treatment is and how strong the evidence is. Not sure about ESMO, but NCCN even publishes a patient-friendly version now.

If guidelines treatments fail (which would likely take a while as there are multiple lines of therapy) then you're getting into the clinical trial space and you'd likely need to get input from someone in academics who is close to the space and does research. But major hospitals usually have "tumor boards" where the oncologists get together and go through challenging patient cases and make recommendations on next steps. But sounds like OP is nowhere close to that.