In my experience, no test is conclusive or inconclusive unto itself. I personally have had the 5-HIAA test. My oncologist views it as a small part of the plethora of tests and scans he reviews in diagnosing and treating cancer. I was diagnosed with a pancreatic neuroendocrine tumor that spread in 8/2022. I have been on chemotherapy since. I have had the 5-HIAA test once during the very beginning of treatment. My doctor dismissed the results as "insignificant". What other tests/scans have you done?