Diagnostic value of FDG-PET/CT for peritoneal carcinomatosis (PC) before hyperthermic intraperitoneal chemotherapy (HIPEC) in ovarian cancer.

Abstract

e15574 Background: Evaluate FDG-PET/CT utility for the detection of peritoneal carcinomatosis from ovarian cancer treated by chemotherapy by using surgical and histopathological findings as the standard of reference. Methods: 38 patients (46 to 68 years) with recurrent (n=35) or primary (n=3) ovarian cancer were reviewed for the presence of peritoneal lesions on FDG-PET/CT before cytoreductive surgery and HIPEC treatment. 30 had adenocarcinomas (13 papillary serous, 7 moderately differenciated, 6 poorly differentiated, 3 serous and 1 serous cystadenocarcinoma) and 2 endometrioid tumors. 9 had psammomatous calcifications. All were suspected cases of PC. 35 patients had received adjuvant chemotherapy and 3 neoadjuvant chemotherapy (primary cancer). FDG-PET/CT results were reinterpreted by two experienced nuclear medicine physicians who knew that PC was suspected. The FDG uptake was determined as SUVmax in the most active lesion in all abdomino-pelvic quadrants (average SUVmax= 6.1; range 1.1- 25). SUVmax in the liver was also measured (average SUVmax=2.9). All PET/CT exams were realised on the same machine. Results: FDG PET/CT diagnosed 18 in 32 patients with peritoneal metastases. There was no suspicious site of abnormal FGD uptake in the supradiaphragmatic regions. The sensitivity, specificity and accuracy of FDG PET/CT were respectively 59,100, 66%. The positive and negative predictive value of FDG PET/CT were 100 and 31%. 13 false negative PET/CT findings were due to millimetric or infracentimetric perihepatic, mesenteric and omental implants (unseen on PET/CT) and to nodules less than one centimeter with no significant FDG uptake (SUVmax lower than hepatic uptake). The true negative findings were found after chemotherapy. Conclusions: FDG-PET/CT can be considered as a useful tool for the selection of patients for HIPEC treatment in the absence of distant metastasis. It showed excellent results for the positive diagnosis and tumor burden for lesions more than 1 cm (PPV 100%). The sensitivity was low in the presence of millimetric disease with or without prior chemotherapy before HIPEC.