[giantg2]

There was a New York Times series about rare diseases. It might have been called "Diagnosis". Maybe reaching out to them would be an option. It seems odd that a cancer center can't tell you what type of cancer it is other than malignant cystic cancer, even when consulting with other specialists/ centers.

If you have more info about it, maybe try searching PubMed for articles/cases that match similar descriptions and lab values.

If you can't get any answers then look around for various regimens and suppliments that could help with general cancers, but verify them by finding studies supporting them. Check with the doctors to make sure it won't make things worse or interfere with other treatment.