Cyst fluid iron-related compounds as useful markers to distinguish malignant transformation from benign endometriotic cysts

Abstract

The purpose of this study was to investigate cyst fluid levels of total iron, heme iron and free iron in benign endometriotic cysts and endometriosis-associated ovarian cancer (EAOC) and to demonstrate the significance of these biomarkers in differential diagnosis between EAOC and endometriotic cysts. Cyst fluid samples were obtained from eleven patients with EAOC and thirty-six women with benign endometriotic cysts at the time of surgery. The median (± SD) total iron levels for endometriotic cysts and EAOC cysts were 244.4 ± 204.9 mg/L and 14.2 ± 36.6 mg/L, respectively. EAOC patients had much lower levels of iron-related compounds compared with endometriotic cyst samples (p< 0.001). When the total iron results were analyzed using the receiver operating characteristics (ROC) curve method, the optimum diagnostic cut-off point was 64.8 mg/L, sensitivity was 90.9%, specificity was 100%, positive predictive value (PPV) was 100%, and negative predictive value (NPV) was 97.3%. Patient demographic characteristics such as tumor size, age at operation, parity and menopause were not correlated with cyst fluid iron levels. We conclude for the first time that iron-related compounds are important biomarkers that can predict malignant transformation with high sensitivity and specificity for women with endometriosis.