A Study of Risk Malignancy Index (RMI) in Adnexal masses of a Tertiary Care Hospital

Abstract

Background: Adnexal masses are a common cause for admission of patients to Gynecology clinics, and one of the most common reasons for referral to gynecologic oncology departments for possibility of uterine or ovarian malignancies. The most prevalent type of pelvic masses is ovarian masses, which include benign cysts and tumors. To standardize and improve the pre-operative evaluation, a scoring system of Risk of Malignancy Index-3(RMI-3) as is developed. A cut off value of 200 for RMI revealed the best discrimination between benign and malignant adnexal mass, because of its high sensitivity and specificity levels. Aims and Objectives: (a)To evaluate the effectiveness of risk of RMI-3 in preoperative discrimination between benign and malignant adnexal masses. (b)To arrive at optimal cut off point of RMI-3 score for benign and malignant adnexal mass. (c) To find out the sensitivity, specificity, positive predictive value, negative predictive value and accuracy for RMI-3 score. Method: It is a prospective study conducted in Obstetrics & Gynecology Department of M.K.C.G. Medical College & Hospital, Berhampur; Odisha, India from September 2017 to September 2019 over 130 cases with adnexal masses after approval by IEC. Leading symptoms such as abdominal mass, swelling/discomfort, abdominal pain, gastrointestinal symptoms, urinary symptoms, generalized malaise and fatigue were also checked. All patients underwent routine physical examination followed by breast examination, lymphadenopathy, abdominal examination and pelvic examination. The RMI-3 for each case was calculated using the product of the ultrasound score (U), menopausal score (M) and the absolute value of serum CA-125. RMI was evaluated for sensitivity, specificity, positive predictive value (PPV), negative predictive values (NPV) and diagnostic accuracy with reference to the actual presence of a malignant or benign pelvic tumor. Results: The study included 130 cases with adnexal masses of which 85 cases (65.4%) are benign and 45 cases (34.6%) are malignant. Among all 81 cases (62.3 %) had an ultrasound score of 1 while 49 cases (37.7%) had scored 3. Of the 81 cases with ultrasound score 1, 72 cases (88.9%) had benign and 9 cases (11.1%) had malignant diseases. Of the 49 cases with ultrasound score of 3, 13 cases (26.5%) had benign and 36 cases (73.5%) had malignant diseases. With CA-125 of 35 U/ml as cut off, 52 cases (40%) had less than 35 IU/ml and 78 cases (60%) had more than 35 U/ml. Out of 52 cases with CA-125 < 35 U/ml, 41 cases (78.8%) had benign and 11cases (21.2%) had malignant diseases. Out of 78 cases with CA-125 > 35 U/ml, 44 cases (56.4%) had benign and 34 cases (43.6%) had malignant lesions. Out of 93 patients with RMI < 200, 11 cases (11.8%) have malignant and 82 cases (88.2%) have benign diseases. Of 37 cases with RMI > 200, 34 cases (91.9%) have malignant and 3 cases (8.1%) have benign diseases. The best performance for RMI-3 was at cut-off point 225 with highest area under the ROC curve is 87% with sensitivity of 75.55%, specificity of 98.82%, PPV of 97.14%, NPV of 88.42% and an accuracy of 90.76%. RMI-3 at cut off value of 200 gives sensitivity of 75.5%, specificity of 96.4%, PPV of 91.89%, NPV of 88.17% and accuracy of 86.92%. Among all cases, 95 cases (73.1%) had RMI < 225 and out of which 84 cases (88.5%) were benign and 11 cases (11.5%) were malignant. Among 35 cases (26.9%) with RMI >225, one case (2.9%) was benign and 34 cases (97.1%) were malignant lesions (p<0.05). Among the criteria RMI-3 score > 225 has highest sensitivity, specificity, PPV, NPV and diagnostic accuracy when compared with individual parameters. Conclusion: RMI-3 was a better estimate in diagnosing adnexal masses  with high risk of malignancy and subsequently guiding the patients to gynecological oncology centers for suitable and effective surgical interventions compared with individual parameters of ultrasound score or CA-125 or menopausal score.