Proposed classification of pseudomyxoma peritonei: influence of signet ring cells on survival
Shreya Shetty1, Bala Natarajan, Peter Thomas
1Department of Surgery, Creighton University Medical Center, Omaha, Nebraska, USA.
Abstract:
The nomenclature and classification of pseudomyxoma peritonei (PMP) is confusing and controversial. Numerous classification systems have been proposed, none of which are easily reproducible or a useful guide for treatment. Patients with PMP of appendiceal origin were identified from our institution's database. Kaplan-Meier analyses were performed based on a proposed new PMP classification, a three-tiered grading system designated PMP1, PMP2, and PMP3. These results were compared with the established schemes by Ronnett and Bradley et al. There were 211 patients included in the analysis with a mean age of 51 ± 12 years at diagnosis. For PMP1, 86 patients (40.8%) included cases with abundant extracellular mucin and columnar nonstratified epithelium without dysplasia or atypia. For PMP3, 50 patients (23.7%) consisted of PMP with any percentage of signet ring cells (SRCs), For PMP2, 75 patients (35.5%) included all other patients. The mean age (± standard deviation) for PMP 1, 2, and 3 were 51 ± 12, 51 ± 12, and 51 ± 10 years, respectively (P = 0.90). The three groups had similar sex distribution (P = 0.24) and resection status (P = 0.47). Kaplan-Meier analyses showed median survivals of 120, 88, and 40 months and 5-year survival rates of 85.7, 63.05, and 32.2 per cent (P < 0.0001) for PMP 1, 2, and 3, respectively. Three distinct categories, PMP1, 2, and 3, were identified, which provide better stratification in terms of overall survival and represent differences in tumor biology that may impact treatment recommendations.
Insights
A new classification system for pseudomyxoma peritonei (PMP) effectively stratifies patients into three distinct groups (PMP1, PMP2, PMP3). This grading system correlates with significant differences in overall survival, aiding treatment decisions for appendiceal PMP.
Area of Science:
- Oncology
- Gastroenterology
- Pathology
Background:
- Pseudomyxoma peritonei (PMP) classification is complex and lacks reproducibility, hindering effective treatment strategies.
- Existing classification systems do not adequately guide clinical management or reflect disease prognosis.
- Appendiceal origin is a common source of PMP, necessitating a clear prognostic stratification.
Purpose of the Study:
- To develop and validate a novel, reproducible three-tiered classification system for pseudomyxoma peritonei (PMP) of appendiceal origin.
- To assess the prognostic value of the proposed PMP classification (PMP1, PMP2, PMP3) in terms of patient survival.
- To compare the efficacy of the new classification with established schemes.
Main Methods:
- Retrospective analysis of 211 patients diagnosed with PMP of appendiceal origin.
- Application of a new three-tiered grading system: PMP1 (abundant mucin, nonstratified epithelium), PMP3 (any signet ring cells), and PMP2 (all other cases).
- Kaplan-Meier survival analyses were performed and compared with existing classification systems (Ronnett, Bradley et al.).
Main Results:
- The new classification identified three distinct groups: PMP1 (40.8%), PMP2 (35.5%), and PMP3 (23.7%).
- Kaplan-Meier analysis revealed significantly different median survivals (120, 88, and 40 months) and 5-year survival rates (85.7%, 63.05%, 32.2%) for PMP1, PMP2, and PMP3, respectively (P < 0.0001).
- Patient demographics, sex distribution, and resection status were similar across the three newly defined PMP groups.
Conclusions:
- The proposed PMP1, PMP2, and PMP3 classification provides superior prognostic stratification for appendiceal PMP compared to existing systems.
- This grading system reflects underlying differences in tumor biology, offering valuable insights for tailoring treatment recommendations.
- The new classification enhances the ability to predict patient outcomes and guide therapeutic interventions in pseudomyxoma peritonei.
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