Abstract: The present invention relates to a broad cancer immunoassay. Specifically, an immunoassay for peptides associated with oncogenic processes such as metastatic proteolysis is disclosed. In an illustrative embodiment, the immunoassay utilizes antibodies which bind to peptides which are generated by proteolytic processes and which contain epitopes which are masked in undegraded blood proteins such as fibrinogen. Detection of such degradation peptides in a biological sample by immunological methods allows the diagnosis of a wide variety of cancers.