What It’s Measuring

So I recently emailed my nurse and asked what, exactly, the tumor marker test measures, and she called back the other day and told me this, which isn't a huge amount of information, but was all that she and Dr Specht knew. Basically, the test is a measure of the amount of a certain type of protein in the bloodstream, a protein sloughed off by tumors. No one knows, however, if it is only present when there are active tumors. We are assuming it's not; that dead, or maybe even dormant, tumors/cancer cells would also slough the protein. It turns out that there are a lot, a very lot, of things we don't know about cancer. Well, duh.