External multicentre validation of pseudomyxoma peritonei PSOGI-Ki67 classification

• DOI: 10.1016/j.ejso.2023.03.206
• Publication Date: 2023-03-15T10:13:50Z
• Authors: A. Arjona-Sanchez; A. Martinez-López; M.T. Moreno-Montilla; J. Mulsow; P. Lozano-Lominchar; B. Martínez-Torres; B. Rau; E. Canbay; A. Sommariva; M. Milione; M. Deraco; O. Sgarbura; A. Torgunrud; V. Kepenekian; N.J. Carr; A. Hoorens; J.B. Delhorme; R. Wernert; D. Goere; L. Martin-Roman; S. Cosyns; K. Flatmark; B. Davidson; L. Khellaf; F. Pereira-Perez; L. Rodriguez-Ortiz; A. Ibáñez-Costa; A. Romero-Ruiz; B. Rufián-Andújar; F. Valenzuela-Molina; A. Casado-Adam; J.M. Sánchez-Hidalgo; S. Rufián- Peña; R. Ortega-Salas; M. Granados-Rodrí...; M.C. Vázquez-Borrego; F.I. Bura; J.P. Castaño; S. Kusamura; D. Baratti; M. Guaglio; Pascual A. Angel ...; Ruiz de Valbuena ...; F. Quénet; S. Yilmaz; Torun B. Canbay; E. Sola Vendrell; L. González-Bayón; W. Ceelen; W. Willaert; J. Demuytere; M.E. Alberto-Vilchez; S. Gül-Klein; Glehen Olivier; Isabelle Bonnefoy; Cecile Odin; Laurent Villeneuve; Sylvie Isaac; Nazim Benzerdjeb; Juliette Fontaine; Philippe Bertheau; Maysoun Kassem; Isabelle Sourrouille; Maximiliano Gelli; Charles Honore; Peggy Dartigues; Valérie Boige; Véroniques Verriele; Cécile Brignad; Gerlinde Averous; C. Shields; J. Aird; Antonio Scapinello; Maria Chiara Biatta; Marco Tonello; Chiara Cenzi
• Keywords: Pseudomyxoma Peritonei

Pseudomyxoma peritonei (PMP) is a rare malignant disease. Adding of the Ki67 proliferation index to the PSOGI PMP classification provided two different subcategories of the extensive HG-PMP group (HG-PMP ≤15% and HG-PMP >15%) with different survival in a previous unicentric study. This study aims to carry out an external and multicentre validation of this new proposed classification.It was a prospective analysis of samples from a historical and international cohort of patients. A representative area with higher cellular density was used to determine the Ki67%. The Ki67 proliferation index (%) was determined in all the HG-PMP patients. A Cox proportional hazard models and multivariable COX models were used. The Kaplan-Meier method and the two-tailed log-rank test were used to analyse the effect of different PSOGI-Ki67 categories on OS and DFS. Its predictive accuracy was analysed using Harrel's C-index and the ROC curve. The calibration was performed using the calibration plots matching.After exclusions, 349 patients were available for analysis. The 5-years OS were 86% for LG-PMP, 59% for HG-PMP≤15, 38% for HG-PMP>15 and 42% for SRC-PMP (p = 0.0001). The 5-years DFS were 49% for LG-PMP, 35% for HG-PMP≤15, 16% for HG-PMP>15 and 18% SRC-PMP (p = 0.0001). The discrimination capability of PSOGI-Ki67 was validated.the PSOGI-Ki67 classification discriminates and predicts the OS and DFS in patients with PMP dividing the HG-PMP category into two well-defined sub-categories. The Ki67 proliferation index should be incorporated routinely in the pathology report for these patients.