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Which classification system defines best prognosis of mucinous neoplasms of the appendix with peritoneal dissemination: TNM vs PSOGI?
  1. Lorena Martín-Román1,2,
  2. Pablo Lozano2,3,
  3. Yesica Gómez4,
  4. María Jesús Fernández-Aceñero4,
  5. Wenceslao Vasquez2,3,
  6. Natividad Palencia3,
  7. Luis González-Bayón2,3
  1. 1 General Surgery, Hospital General Universitario Gregorio Marañón, Madrid, Spain
  2. 2 Complutense University of Madrid Faculty of Medicine, Madrid, Comunidad de Madrid, Spain
  3. 3 Peritoneal Carcinomatosis Unit, Department of General Surgery, Hospital General Universitario Gregorio Marañón, Madrid, Spain
  4. 4 Department of Pathology, Hospital General Universitario Gregorio Marañón, Madrid, Spain
  1. Correspondence to Dr Luis González-Bayón, Peritoneal Carcinomatosis Unit, Department of General Surgery, Hospital General Universitario Gregorio Marañón, Madrid, Spain; lgbayon{at}


Aims Several classification systems are used for pseudomyxoma peritonei. The four-tiered classification system proposed by Peritoneal Surface Oncology Group International (PSOGI) and the two-tiered proposed by the eighth edition of the American Joint Committee on Cancer (AJCC) result from evolution in terminology and pathological insight. The aim is to evaluate the impact of PSOGI and eighth edition of the AJCC classifications on survival.

Methods Pathological slides were reviewed from a prospectively maintained database including patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for an appendiceal mucinous neoplasm with peritoneal dissemination between January 2009 and December 2019. Patients were reclassified according to PSOGI and AJCC eighth edition criteria. Survival analysis evaluated the impact of each classification system on overall survival (OS) and disease-free survival (DFS) while the concordance-index evaluated their predictive power.

Results 95 patients were identified; 21.1% were reclassified as acellular mucin, 55.8% as low-grade mucinous carcinoma peritonei, 8.4% as high-grade MCP (HGMCP) and 14 as HGMCP with signet ring cells. Median OS was not reached, 5-year OS and DFS were 86.1% and 51.5%, respectively. Multivariate analysis revealed significant associations with OS (PSOGI: HR 10.2, p=0.039; AJCC: HR 7.7, p=0.002) and DFS (PSOGI: HR 12.7, p=0.001; AJCC: HR 3.7, p<0.001). The predictive capacity of both classification systems was unacceptable for OS and DFS (concordance-index values <0.7).

Conclusions Both classification systems behaved similarly when stratifying our series into prognostic groups. The PSOGI classification provides better histopathological description, but histology alone is insufficient for adequate patient prognostication.

  • appendix
  • chemotherapy
  • cancer
  • regional perfusion
  • neoplasms
  • peritoneum

Data availability statement

No data are available.

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  • Handling editor Runjan Chetty.

  • Contributors LM-R: Conceptualisation, investigation, formal analysis, writing—original draft preparation, guarantor. PL: Conceptualisation, methodology, formal analysis, writing—reviewing and editing. YG: Investigation, resources. MJF-A: Conceptualisation, investigation, resources, writing—reviewing and editing. WV: Conceptualisation, methodology, data curation, formal analysis. NP: Investigation, data curation. LG-B: Conceptualisation, methodology, writing—reviewing and editing, supervision.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.