Extreme elevation of CA19-9 in patient with endometriosis-associated cancer: A brief report and review of the literature

CA 19-9 (carbohydrate antigen 19-9) is used as a biomarker for hepatobiliary cancer and is generally not considered helpful in the evaluation of gynecologic cancer. Endometriosis-associated cancers are a subset of gynecologic cancers in which malignancy is found adjacent to endometriosis either within or outside the gynecologic tract. We describe a case of a woman who presented with a CA 19-9 level of 49,469 U/mL who was subsequently found to have two concurrent but separate primary endometriosis-associated cancers involving the ovary and small intestine. Although data regarding the association between CA 19-9 and endometriosis-associated malignancy is lacking, endometriosis is known to be associated with high levels of inflammation which in turn has been associated with higher CA 19-9 levels. The inflammatory response and effect on CA 19-9 levels may be particularly pronounced in cases where endometriosis-associated malignancy involves the peritoneum. The case described suggests that when cancer is suspected in a woman with an extremely high level of CA 19-9 and no apparent hepatobiliary disease, an endometriosis-associated malignancy may be a consideration.