my cancer was unknown primary for quite sometime. my doctor at Stanford had extensive testing done and eventually sent my samples to an external lab that does advance "point of origin" testing. Early indications from mutations and variants found in the testing led us to believe it could have originated in the GI tract or the lungs. PET and CT scans at first showed no cancer anywhere but my neck. So I went through colonoscopy, several endoscopies, traditional as well as a video capsule to make sure we checked the small intestine. I think I was getting CTs and PETs every 2-4 months with 6 weeks being the shortest. eventually a few nodes surfaced in my lungs, and the point of origin testing came back with 97% certainty that this was the primary. it has recurred in my neck after having surgery and radiation last year. I start systemic treatment in July.