Work

Peritoneal metastasis histological grade independently predicts outcome in pseudomyxoma peritonei treated with curative surgery

Year: 2026

Type: article

Abstract: BACKGROUND: Pseudomyxoma Peritonei is characterised by peritoneal metastasis from appendiceal mucinous neoplasms (AMN). The PSOGI classification (2016) categorises PMP into acellular mucin (AM), low-grade mucinous carcinoma peritonei (LGMCP), and high-grade mucinous carcinoma peritonei (HGMCP). This study aimed to determine long-term prognosis based on this classification. MATERIALS AND METHODS: Pathology review from PMP patients with AMNs undergoing cytoreductive surgery and heated intraperitoneal chemotherapy (CRS + HIPEC) with curative intent over a 15-year period (2006-2021) was undertaken. Patients underwent standardised surveillance. Cox proportional hazards regression models, log-rank test, and Kaplan-Meier method were used to assess overall (OS) and disease-free survival (DFS) based on histopathological peritoneal metastasis grade. DFS was only calculated for patients who had a complete cytoreduction. RESULTS: 290 PMP patients were identified (AM = 34%, LGMCP = 59%, HGMCP = 7%) with median follow-up of 49 months. Median age was 59 years (range: 22-79), M: F of 1:2.5, peritoneal cancer index median of 18 (range: 0-39). Univariate OS hazard ratio (HR) is 2.75 for LGMCP vs AM (95% CI: 1.05 -7.21, p < 0.040) and 14.29 for HGMCP vs AM (95% CI: 3.92- 52.11, p < 0.001). DFS HR = 5.15 for LGMCP (95% CI: 2.19-12.10, p < 0.001) and 4.16 for HGMCP (95% CI: 1.03-16.80, p < 0.045) with an overall peritoneal metastasis p value < 0.001. Multivariate OS analysis showed that peritoneal histology for HGMCP remained a significant predictor of poor prognosis for OS (HR: 5.54, 95% CI: 1.32-23.25, p = 0.019), whilst LGMCP did not demonstrate a significant association (HR: 1.59, 95% CI: 0.59-4.26, p = 0.359). DISCUSSION: Peritoneal metastasis histopathological grade predicts outcome for patients with PMP from AMN following CRS + HIPEC independent of primary histology.

Source: Clinical & Translational Oncology

DOI: 10.1007/s12094-025-04112-8