Value of an 18F-FDG-based peritoneal cancer index in predicting tumor grade, tumor burden, and completeness of cytoreductive surgery in epithelial ovarian cancer

Abstract

Background The challenge of treating epithelial ovarian cancer (EOC) is significantly heightened by peritoneal metastasis. ¹⁸F-FDG PET/CT is employed as a preoperative assessment method for evaluating the extent of peritoneal spread in EOC, while peritoneal cancer index (PCI) serves as a vital tool in assessing peritoneal dissemination during surgery. We sought to investigate the value of a PCI derived from ¹⁸F-FDG PET/CT (PET-PCI) in predicting tumor pathological grade, tumor burden, and completeness of cytoreductive surgery (CRS) in patients with EOC. Methods We conducted a retrospective analysis of 64 patients with the International Federation of Gynecology and Obstetrics (FIGO) stages III–IV or recurrent EOC with peritoneal metastasis who underwent 18F-FDG PET/CT before therapy. PET-PCI was calculated by summing the 18F-FDG uptake scores across 13 abdominopelvic regions. Among them, 23 patients underwent CRS within 2 months after 18F-PET/CT. The relationship between PET-PCI, histological type (I or II), and surgical PCI was analyzed, as was the ability of PET-PCI to predict the completeness of CRS. Results Pathological analysis revealed 14 patients with type I and 50 patients with type II tumors. Compared to patients with type I tumors, those with type II tumors exhibited higher PET-PCI values (19.0 ± 11.1 vs. 12.4 ± 11.5 points, p = 0.022). Setting a cutoff of 15 points for PET-PCI to identify type II EOC resulted in a sensitivity of 56.0%, a specificity of 78.6%, and an AUC of 0.701 (p = 0.023). PET-PCI exhibited a positive correlation with surgical PCI (r = 0.885, p < 0.001). PET-PCI was a significant predictor of CRS completeness, with an AUC of 0.967 (p = 0.004). The cutoff value of 16 for PET-PCI facilitated the identification of CRS completeness in EOC patients, providing a sensitivity of 84.2% and a specificity of 100%. Conclusions This study demonstrated that PET-PCI is a valuable parameter in predicting tumor grade and burden in patients with advanced EOC. Moreover, PET-PCI may serve as a tool for predicting CRS completeness.