Abstract
Background
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.
Method
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.
Results
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.
Conclusion: 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.
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Article info
Publication history
Published online: March 14, 2023
Accepted:
March 9,
2023
Received in revised form:
March 2,
2023
Received:
November 2,
2022
Publication stage
In Press Journal Pre-ProofIdentification
Copyright
© 2023 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.
