Prognostic role of radiological peritoneal cancer index in malignant peritoneal mesothelioma: national cohort study

Abstract

Malignant peritoneal mesothelioma (MpeM) is a rare cancer of the mesothelial cells of the peritoneum. Computed tomography (CT) is considered the standard for first-line imaging of MPeM, diagnosis and risk stratification remains challenging. Peritoneal cancer index (PCI), as assessed by CT, is utilized in the prognostic assessment of other malignant intra-abdominal conditions; however, there is limited data concerning the utility of PCI in the diagnosis and workup of MPeM. We studied a retrospective cohort of all patients diagnosed with MPeM from 2000 to 2012 in Finland. CT and magnetic resonance imaging (MRI) were reviewed and scored by an experienced and blinded, board-certified abdominal radiologist. Additional clinical data and outcomes were obtained from Finnish Cancer Registry (FCR), the Workers' Compensations Center (WCC), and Statistics Finland (SF). Abdominal CT or MRI was available for 53 of 90 patients. The median radiographic PCI was 25. PCI score was correlated with overall survival (p = 0.004, Exp(B) = 1.064, 95% CI 1.020-1.110). PCI score ≥ 30 was associated with worse survival (p = 0.002), while PCI ≤ 19 was associated with improved overall survival (p = 0.001). Our study indicates that radiological pci is prognostic in MpeM and should be assessed during radiographic workup and integrated into clinical decision-making. Malignant peritoneal mesothelioma (MPeM) is a rare cancer of the mesothelial cells of peritoneum, representing 7-30% of all mesothelioma diagnoses. 1 Signs and symptoms of MPeM are non-specific and include abdominal pain, abdominal distension, and weight loss. Given the rarity of the diagnosis and the non-specific presentation, diagnosis is often delayed. 2,3 Previous reports have indicated median time of 4-6 months between initial presentation and diagnosis. 4 Computed tomography (CT) of the chest, abdomen, and pelvis is the first-line imaging modality in the diagnostic workup of MPeM. 5 Ascites, peritoneal thickening, omental disease, small bowel involvement and solid and cystic masses are typical of MPeM on CT. 6-8 However, the sensitivity and specificity of CT in the diagnosis of MPeP is not described in the literature. The role of PET-CT in the diagnosis and workup of MPeM is likewise unclear. 9 Peritoneal mesothelioma is not well suited to traditional classification schemes like the TNM staging due to the rarity of distant metastases and the difficulty in discerning the full extent primary tumor versus local/regional spread. Several staging systems for MPeM have been proposed but to date have not been widely adopted. 10 Peritoneal cancer index (PCI) is a measure of disease spread developed for peritoneal carcinomatosis

Incidence, Survival Analysis and Future Perspective of Primary Peritoneal Mesothelioma (PPM): A Population-Based Study from SEER Database

“…PCI for peritoneal spread of the disease is evaluated using either laparotomy or computed tomography. A high PCI score is associated with a worse prognosis [ 12 ]. However, the subclassification of epithelioid mesothelioma and data on the peritoneal cancer index are not available in the SEER registry.…”

Methylthioadenosine Phosphorylase and Breast Cancer 1 Protein-Associated Protein 1 as Biomarkers for the Peritoneal Mesothelioma

“…PCI score (range 0-39) can evaluate the spread of peritoneal cancer during laparotomy or CT examination. 24 The residual tumors were intraoperatively classified by CC scores, including 4 groups: CC-0 (no residual tumors), CC-1 (residual tumor with a diameter of <2.5 mm), CC-2 (residual tumor with a diameter of between 2.5 mm and 2.5 cm), and CC-3 (residual tumor with a diameter of >2.5 cm). 25 Previous study had shown that PCI score and CC score were related to the prognosis of PeM.…”

Communicating imaging findings in peritoneal mesothelioma: the impact of ‘PAUSE’ on surgical decision-making

“…A radiological study of 59 patients with peritoneal mesothelioma showed significantly higher rPCI (34 vs. 17), large volume upper abdominal disease, small bowel and mesenteric disease among patients who had incomplete cytoreduction for malignant peritoneal mesothelioma compared to those who had complete cytoreduction [21]. CT or MRI-derived rPCI of ≥ 30 was associated with worse survival and rPCI of ≤ 19 was associated with improved survival in another study of 53 patients with malignant peritoneal mesothelioma [49]. Thus, CT is a good technique for identifying patients with high PCI disease, who may not benefit from CRS and HIPEC.…”