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Colorectal
PWE-097 Classification of pseudomyxoma peritonei as low or high grade according to the WHO criteria is prognostically significant
  1. N Carr1,
  2. B Moran2,
  3. T Cecil2,
  4. K Chandrakumaran2,
  5. I C Ilesley3,
  6. A Mirnezami4,
  7. F Mohamed2
  1. 1Faculty of Medicine, University of Southampton, Southampton, UK
  2. 2Pseudomyxoma Centre, Basingstoke and North Hampshire NHS Foundation Trust, Basingstoke, UK
  3. 3Histopathology, Basingstoke and North Hampshire NHS Foundation Trust, Basingstoke, UK
  4. 4Department of Surgery, University Hospitals Southampton, Southampton, UK

Abstract

Introduction The current WHO classification of tumours of the digestive system divides pseudomyxoma peritonei into two grades, namely low-grade and high-grade. This study was designed to correlate survival with low-grade and high-grade pseudomyxoma peritonei classified according to the WHO criteria.

Methods The histological slides of 274 consecutive patients were reviewed and designated as either low-grade or high-grade. The patients had been referred for cytoreductive surgery. The grade of the pseudomyxoma was correlated with survival data using the Kaplan–Meier method with the log-rank (Mantel-Cox) test.

Results 238 (87%) patients had low-grade lesions and 36 (13%) had high-grade lesions. The most common primary tumour was a low grade appendiceal mucinous neoplasm (231 cases, 84%). Seven patients who died within 30 days of their operation (a postoperative mortality of 2.6%) were excluded from survival analysis. Another patient was excluded because of incomplete survival data. The remaining 266 patients showed an overall 5-year survival of 63% in patients with low-grade pseudomyxoma peritonei and 23% in patients with high-grade pseudomyxoma peritonei (p<0.001). Complete cytoreduction was achieved in 165 (60%) patients; the 5-year survival for low-grade and high-grade was 84% and 48% respectively in this group (p<0.001). The median survival of patients who had complete cytoreduction was 7.7 years for low-grade and 2.8 years for high-grade (p<0.001).

Conclusion Histological classification of pseudomyxoma peritonei as low-grade or high-grade correlates with prognosis. This may identify a group who could benefit from further adjuvant therapy which is not generally advocated for appendiceal mucinous tumours.

Competing interests None declared.

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