Can someone explain the oncoblot test that states it can identify 26 types of cancers with a blood test?

Yes: There is a protein that only exists on the surface of these types of cancer cells that the test detects well enough to be the choice in Nat'l Agency research efforts. Here's a clear explanation from a website - there are many. http://www.cancercenterforhealing.com/early-cancer-detection/ Best!

Has tumor marker: The oncoblot test relies on identification of a surface tumor marker,the ENOX2 protein. This is a growth factor protein that appears in a large array of malignancies, not in normal tissue. The 26 tumors that express it are lumped , but not distinguishable as to type. This is similar to mutated mitochondrial DNA present on all tumors and shed in the serum. A good marker is tumor specific.