The present invention is directed to the detection and quantification of total ras p21 in body fluids, particularly serial changes of total ras p21 levels in a subject's body fluids. Further, the invention is directed to detecting and quantitating total ras p21 in conjunction with one or more other proteins, such as, oncoproteins, angiogenic factors, tumor markers, inhibitors, growth factor receptors, metastasis proteins, and tumor suppressors. The disclosed methods are diagnostic/prognostic for preneoplastic/neoplastic diseases, and useful to select therapies for patients with preneoplastic/neoplastic diseases. The disclosed methods are further useful to monitor the status of a patient's preneoplastic/neoplastic disease, and/or to monitor how a patient is responding to an anticancer therapy.