A method for detecting the presence of cancer employs monoclonal antibody OXA or OXB, antibodies which bind to the antigen bound by monoclonal antibody OXA or OXB, or fragments of the foregoing which bind to the antigen bound by monoclonal antibody OXA or OXB. The method comprises contacting a sample of a biological fluid from a subject with the antibody under conditions permitting the antibody to form a reaction product, and then detecting the presence or absence of the reaction product. The method is particularly useful for monitoring the progression of treatment in a patient previously diagnosed as having ovarian cancer. The method is also useful for detecting and monitoring endometrial cancer.