EVALUATION OF A RISK OF MALIGNANCY INDEX BASED ON SERUM CA125, ULTRASOUND FINDINGS AND MENOPAUSAL STATUS IN THE PREOPERATIVE DIAGNOSIS OF PELVIC MASSES

Objective To evaluate the ability of a risk of malignancy index (RMI), based on a serum CA125 level, ultrasound findings and menopausal stat us, to discriminate a benign from a malignant pelvic mass and to discr iminate early stage (Figo Stage I) from Stages II, III and IV of ovari an cancer. Design A prospective study. Setting Department of Gynaecolo gy, Trondheim University Hospital, Trondheim, Norway. Participants One hundred and seventy-three women, 30 years or older, consecutively adm itted between February 1992 and February 1994 for primary laparotomy o f a pelvic mass. Main outcome measures The sensitivity, specificity an d positive predictive value of serum CA125 level, ultrasound findings and menopausal status, separately and combined into the RMI, to diagno se ovarian cancer. Results The RMI was more accurate than any individu al criterion in diagnosing cancer. Using a RMI cut-off level of 200 to indicate malignancy, the RMI derived from this dataset gave a sensiti vity of 80%, specificity of 92% and positive predictive value of 83%. Applying RMI criteria developed by others, the following test performa nce was found: sensitivity 71%, specificity 96% and positive predictiv e value 89%. For the Stages II, III and IV of ovarian cancer the sensi tivity increased to approximately 90% without any substantial loss in specificity. Conclusions The risk of malignancy index is able to corre ctly discriminate between malignant and benign pelvic masses. It is a scoring system which can be introduced easily into clinical practice t o facilitate the selection of patients for primary surgery at an oncol ogical unit.