What is the best indicator of cancer: "tumor markers" or "paraneoplastic autoantibodies"? i have signs of cancer and neurological autoimmunity.

Clinical settings: I assume you do not have a diagnosis of cancer- but you are thinking you may have cancer that explains your symptoms? The best indicators would be the clinical settings and to evaluate if other conditions- not just cancer- can explain your symptoms. Neither cancer marker nor autoimmune antibody is specific enough to make a diagnosis of cancer. Paraneoplastic syndrome is not a common condition.

Neither: There are only a handful of very rare circumstances where a "tumor marker" blood test can prove that someone has a cancer. This is because many tumor markers can be elevated by other causes. Paraneoplastic autoantibodies do not diagnose cancer but are called that when a patient with a known cancer has autoantibodies without another known cause.