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Fluorodeoxyglucose PET/CT-derived Metabolic Peritoneal Cancer Index for survival assessment in peritoneal
Semra Demirtaş Şenlik1, Alev Noyaner Çinar2, Ceren Özge Engür Uyanik2
1Department of Nuclear Medicine, University of Health Sciences Ankara Dr. Abdurrahman Yurtaslan Oncology Training and Research Hospital.
Objective:
To evaluate the association between the Metabolically active Peritoneal Cancer Index (M-PCI) derived from 18F-fluorodeoxyglucose PET/computed tomography (18F-FDG PET/CT) and to assess its ability to predict overall survival (OS) in patients with peritoneal carcinomatosis.
Methods:
This retrospective study included 107 patients with pathologically confirmed peritoneal carcinomatosis who underwent 18F-FDG PET/CT between October 2022 and July 2025. M-PCI was calculated using a PET-adapted Peritoneal Cancer Index approach based on metabolically active peritoneal lesions across 13 anatomical regions. Patients were stratified using an M-PCI cutoff value of 20, with the appropriateness of this threshold additionally explored using receiver operating characteristic analysis. Survival analysis was performed using Kaplan-Meier analysis and univariable and multivariable Cox regression models.
Results:
During a median follow-up of 22 months, 78 deaths (72.9%) occurred. The median OS was 9 months. M-PCI was significantly associated with OS [hazard ratio = 1.050 per unit increase; 95% confidence interval (CI) = 1.019-1.082; P = 0.001]. Patients with M-PCI > 20 had significantly worse survival compared with those with M-PCI ≤ 20 (median OS = 3 vs. 10 months; log-rank P = 0.010), with nearly a two-fold increase in mortality risk (hazard ratio = 1.94; 95% CI = 1.14-3.32; P = 0.015). The prognostic impact of M-PCI was particularly pronounced in the gynecologic subgroup. In multivariable Cox regression analysis, M-PCI remained independently associated with OS after adjustment for tumor origin, treatment, extent of disease, ascites, and timing of peritoneal carcinomatosis (adjusted hazard ratio = 1.040; 95% CI = 1.002-1.080; P = 0.042).
Conclusion:
M-PCI derived from 18F-FDG PET/CT is a significant predictor of OS in patients with peritoneal carcinomatosis. By integrating metabolic activity with spatial disease distribution, M-PCI may provide clinically relevant prognostic information and improve risk stratification in this patient population.
