ROLE OF INTEGRATED PET/CT IN DETECTING RECURRENT OVARIAN CANCER IN PATIENTS WITH RISING CA-125 LEVELS

Abstract

Purpose: The purpose of this study was to assess the sensitivity and diagnostic accuracy of integrated positron emission tomography/computed tomography (PET/CT) in detecting recurrent ovarian cancer in treated patients presenting with rising CA-125 levels during clinical follow-up and compare it with those of CT alone. Materials and Methods: This was a retrospective study. We evaluated 45 patients with pathologically proven ovarian carcinoma who underwent PET/CT during October 2010–November 2013 at our institution for suspected relapse; IRB deemed that approval for this retrospective study was not required. Of these, 35 patients who presented with rising CA-125 levels during clinical follow-up were included in this study. Remaining 10 patients were excluded as they had normal CA-125 levels. At least three previous consecutive CA-125 readings and initial conventional imaging before uorodeoxyglucose-PET/CT were noted. Sensitivity and diagnostic accuracy for tumour detection with PET/CT and CT alone were calculated; histological analysis after biopsy/second look surgery or clinical- radiologic follow-up/response to chemotherapy was taken as reference standard. K statistics (Cohen K) was used for statistical analysis. Results: Of 35 patients with suspected relapse, one patient was lost to follow up. 30 patients were documented to have relapsed, while in four patients, recurrence was not identi ed either on CT or PET-CT and they were proved to be disease free on 2-year follow-up. Amongst these relapsed patients, 10/30 cases were proven histologically, 3 with imaging-guided biopsy and 7 with second-look surgery, whereas 20/30 were con rmed on clinical/radiological follow-up (ranging from 3 to 6 months) or by response to chemotherapy on subsequent imaging. Of 30 patients with relapse, PET-CT highlighted recurrence in 27. Sensitivity, speci city, positive predictive value, negative predictive value, and diagnostic accuracy of integrated PET/CT were calculated to be 90%, 75%, 96%, 50%, and 88%, respectively. CT alone detected recurrence in 20 patients. Sensitivity, speci city, positive predictive value, negative predictive value, and diagnostic accuracy of CT were calculated to be 73.3%, 100%, 100%, 33%, and 76%, respectively. Conclusion: PET/CT is a highly sensitive and accurate post-therapy surveillance modality for the detection of recurrent ovarian cancer in patients with rising tumour markers as compared to CT alone. Key words: CA125, uorodeoxyglucose, ovarian cancer, positron emission tomography/computed tomography, recurrence