Residual Tumour at CT Scan Based on Radiologic Peritoneal Carcinomatosis Index After Optimal Cytoreduction in Advanced Ovarian Cancer: A True Prognostic Factor.

Introduction: The maximum residual tumour size after surgery is the most important prognostic factor related to survival in advanced ovarian cancer. This parameter can be subjectively determined by the surgeon at the end of the operation and by a radiologist with a postoperative CT scan. CT scans after optimal cytoreduction can reveal residual/progressive disease in a significant percentage of patients, ranging from 21% to 49%. The aim of this study was to validate the PCI scale for the systematic reading of postoperative CT scans in patients with advanced ovarian cancer and to establish it as a new prognostic marker.

Material And Methods: Patients with advanced ovarian cancer (FIGO II-IV), diagnosed between 2007 and 2019 in Hospital La Fe Valencia, in whom cytoreductive surgery was performed (achieving R0 or R1), and in whom a postoperative CT scan was performed between the third and eighth week post-surgery and prior to the start of chemotherapy, were included. Two different radiologists who specialised in gynaecological malignancy performed a blind analysis of the CT scans. They then read the images using the Peritoneal Carcinomatosis Index (PCI) scale, which divides the abdominopelvic cavity into 12 quadrants. Using the Qualitative Assessment (QA) scale, they established the presence or lack of tumour disease in each of these regions, with QA 1-2 being definitely/probably normal, QA 3 indeterminate and QA 4-5 probably/definitely metastatic.

Results: This study included a cohort of 117 patients. The radiological study found measurable tumour disease in up to 49% of patients after optimal primary cytoreduction (R0 or R1). There was "substantial agreement" between the results of the two radiologists according to the Kappa analysis (0.624). Both radiologists' (A and B) findings were related to a significant reduction in both disease-free survival (DFS) and overall survival (OS) in patients with residual disease in the CT scan (QA 4-5) versus those without macroscopic disease (QA 1-3) ( < 0.05).

Conclusions: The finding of radiological tumour disease on a standardised and systematised postsurgical CT scan prior to the initiation of adjuvant chemotherapy is associated with the prognosis of patients with advanced ovarian cancer.