Can routine blood tests find tumors?

Depends on type: Some routine blood tests may make us think there is something else going on. Almost no routine result will make a doctor immediately leap to the "cancer" diagnosis, but some things can be strange. A white blood cell (WBC) count in excess of 200, 000, for instance. Platelet counts >1, 000, 000. But for actual cancer diagnosis, those take very specific tests looking for specific markers.

Not generally: Most tumors are not diagnosable with routine blood tests. Leukemias are one exception in that a complete blood cell count can provide a strong indication for the diagnosis of some leukemias.