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Pseudomyxoma Peritonei of Extra-Appendiceal Origin: A Comparative Study
Dario Baratti1, Shigeki Kusamura1, Massimo Milione2
1Peritoneal Malicnancy Program, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
Background:
Pseudomyxoma peritonei (PMP) usually originates from appendiceal neoplasms and, less commonly, from extra-appendiceal lesions. To date, the clinical and therapeutic implications of extra-appendiceal origin are largely unknown.
Methods:
A prospective database of 225 PMP patients uniformly treated by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) was reviewed to identify cases with extra-appendiceal primaries. Histologically, negative appendix defined extra-appendiceal origin. Clinical, pathological, and immunohistochemical features (cytokeratin [CK]-20, CK-7, CDX-2, MUC-2, MUC-5A) were correlated with the site of origin. PMP was categorized into low or high grade, according to the 2010 World Health Organization (WHO) classification. The main independent variable for survival analysis was appendiceal versus extra-appendiceal primary.
Results:
In 19 patients (8.4 %), PMP origin was the ovary (n = 9), uterine cervix (n = 1), mature cystic teratomas (n = 4), and unknown (n = 5). Appendiceal and extra-appendiceal PMP groups were comparable for all characteristics, except for a prevalence of females in the latter. Median follow-up was 64.1 months (95 % confidence interval [CI] 53.9-80.1), and 10-year overall survival was 63.4 % (median 148.2 months; 95 % CI 131.2-165.2) for appendiceal PMP, and 62.0 % (median not reached) for extra-appendiceal PMP. The difference was not significant at univariate ( p = 0.297) and multivariate analysis (hazard ratio 1.51, 95 % CI 0.78-3.14; p = 0.278). High-grade peritoneal histology (p = 0.007), prior systemic chemotherapy (p = 0.003), more than four visceral resections (p = 0.011), and incomplete cytoreduction (p = 0.021) independently correlated with poorer survival.
Conclusions:
Clinical-pathological features of PMP, and outcome after CRS/HIPEC, did not differ according to the primary site, thus suggesting that PMP is a relatively homogeneous disease that can be produced by a range of histopathologic entities. Extra-appendiceal origin does not contraindicate CRS/HIPEC.
Insights
Pseudomyxoma peritonei (PMP) originating from extra-appendiceal sites shows similar outcomes to appendiceal PMP after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Extra-appendiceal origin does not negatively impact patient prognosis.
Area of Science:
- Oncology
- Surgical Oncology
- Gastroenterology
Background:
- Pseudomyxoma peritonei (PMP) typically arises from appendiceal neoplasms, but extra-appendiceal origins are less common and their clinical implications are not well understood.
- Understanding the characteristics and outcomes of PMP from varied origins is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the clinical, pathological, and survival differences between appendiceal and extra-appendiceal PMP.
- To evaluate the efficacy of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with PMP of different origins.
Main Methods:
- A prospective database of 225 PMP patients treated with CRS and HIPEC was analyzed.
- Patients were classified based on appendiceal versus extra-appendiceal primary origin, with histological confirmation.
- Clinical, pathological, and immunohistochemical features were correlated with origin and survival outcomes.
Main Results:
- 19 patients (8.4%) had extra-appendiceal PMP, originating from the ovary, uterine cervix, or mature cystic teratomas.
- Appendiceal and extra-appendiceal PMP groups showed comparable overall survival rates (10-year survival: 63.4% vs. 62.0%, respectively).
- High-grade histology, prior chemotherapy, extensive resections, and incomplete cytoreduction were independent predictors of poorer survival.
Conclusions:
- PMP appears to be a relatively homogeneous disease regardless of primary site, with similar clinical-pathological features and outcomes after CRS/HIPEC.
- Extra-appendiceal origin of PMP does not contraindicate CRS/HIPEC and does not adversely affect survival.
- The study highlights the importance of complete cytoreduction and managing high-grade disease for improved patient outcomes.
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