The value of early detection is clear from current tests for specific cancers: self-examination and mammography for breast, prostate-specific antigen (PSA) for prostate, and Pap smears for cervical cancers. No such method exists for early detection of lung cancer. New methods are being designed to test for the very few tumor cells released early in cancer progression into blood (or other body fluids). Single markers for specific cancers have been reported in blood samples or other accessible sites, but these vary between patients. We propose that sets of markers provide a reproducible general pattern, more certain for cancer detection. We have found a dozen markers present in 3 mL blood samples from cancer patients that are absent in blood samples from normal individuals (1 ,2 ).
