Abstract: The present invention relates to the discovery of soluble isoforms of an Epidermal Growth Factor Receptor, or sErbB1 variants, the provision of the sequences of nucleic acids encoding these isoforms, purified recombinant proteins, novel antibodies specific for these isoforms, and the use of immunoassay and other protein assay techniques to measure the concentration of these protein isoforms in a patient biological sample in the femtomolar range. The present invention also provides methods for determining the presence of an ovarian carcinoma in the patient by assaying the concentration of soluble ErbB1 variants in a biological sample from a patient.

Abstract: Embodiments of the present invention relate to p110 soluble EGFR (p110 sEGFR) peptides and nucleic acid sequences. Antibodies, methods of detection, kits, and expression vectors for p110 sEGFR are disclosed. In addition, assays on biological samples for determining and evaluating risk assessment and cancer prevention, screening and early detection, diagnosis, prognosis, theragnosis, monitoring of responsiveness to treatment, and monitoring of disease progression, recurrence, or metastasis of a cancer, are disclosed. In examples, a lower p110 sEGFR concentration adjusted for demographical and physiological variables and other biomarkers is associated with cancer. Therapeutics and methods of treating a cancer related to p110 sEGFR also are embodied herein.