Biomarker proteins that can be used in the diagnosis of early-stage ovarian cancer (OC) are described. The biomarker panels not only permit the distinction of patients with ovarian neoplasia (benign or malignant) from normal subjects, but they also allow the identification of patients with early-stage (stage I/II) ovarian cancer from those patients with benign ovarian tumors or normal individuals. The invention additionally provides methods for detecting and treating various cancers, including cancer of the ovary using OC-related molecules.