Sometimes the cancer doesn't emit any marker proteins, or maybe the ones it does are difficult to detect/create antibodies to bind to. (I'm in the same situati

Sometimes the cancer doesn't emit any marker proteins, or maybe the ones it does are difficult to detect/create antibodies to bind to. (I'm in the same situation as 2 above, I'm a software engineer with domain knowledge from working in a cancer research lab at a university; I may be entirely wrong.)