Treatment for Pseudomyxoma Peritonei (PMP)
Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is the standard of care for resectable and operable pseudomyxoma peritonei, with strong consensus supporting this approach over debulking surgery alone 1, 2.
Primary Treatment Strategy
The definitive treatment for PMP requires complete cytoreductive surgery aimed at removing all visible mucinous disease, immediately followed by HIPEC during the same operative session. This combined approach achieves:
- 5-year survival: 55-64% 2, 3
- 10-year survival: 23-55% 2, 3
- Median survival: 92 months when complete cytoreduction is achieved 3
The survival advantage is substantial compared to debulking surgery alone, despite PMP's known chemoresistance to systemic therapy 2. Complete cytoreduction (CC0-1, meaning no visible residual disease or residual nodules <2.5mm) is achieved in approximately 85-90% of cases at experienced centers and is the most critical prognostic factor 3.
HIPEC Regimen Selection
Two regimens have achieved consensus for clinical use 4:
- Oxaliplatin 200 mg/m² (53% consensus support)
- Cisplatin combined with Mitomycin-C (51% consensus support)
- High-dose Mitomycin-C regimens (89% positive recommendation)
The choice between regimens remains institution-dependent, as randomized trials comparing HIPEC protocols are lacking. The 2022 PSOGI consensus identified comparing these regimens as the highest research priority 4.
Patient Selection Criteria
Proceed with CRS + HIPEC when:
- Disease is deemed resectable on preoperative imaging
- Patient can tolerate major abdominal surgery (typically 8-12 hours operative time)
- No unresectable extraperitoneal metastases present
Imaging evaluation should include:
- CT abdomen/pelvis with IV contrast as the primary staging modality 1
- CT chest with IV contrast for higher-grade appendiceal neoplasms 1
- MRI with DWI may provide superior peritoneal disease detection compared to CT, though CT remains standard 1
Critical Caveat on Imaging Limitations
CT significantly underestimates disease burden. CT peritoneal cancer index (PCI) correlates only 55-70% with surgical findings, with sensitivity of just 11% for nodules <0.5 cm versus 94% for nodules >5 cm 1. Do not deny surgery based solely on CT findings suggesting extensive disease—surgical exploration remains the gold standard for resectability assessment.
Role of HIPEC After Incomplete Cytoreduction
Even when complete cytoreduction cannot be achieved, 70% weak consensus supports performing HIPEC after maximal tumor debulking 4. While outcomes are inferior to complete cytoreduction, this reflects the lack of effective alternative treatments for this chemoresistant disease 2.
Postoperative Surveillance
CT or MRI of abdomen/pelvis is appropriate for follow-up of low-grade PMP 1. However, no formal surveillance guidelines exist—monitoring should be individualized based on:
- Tumor grade (low-grade vs high-grade)
- Completeness of cytoreduction achieved
- CEA levels (CEA ≥5 predicts worse outcomes) 3
Avoid PET/CT for surveillance—it demonstrates poor sensitivity for mucinous peritoneal disease, which is hypometabolic 1.
Quality of Life Outcomes
Long-term survivors (10-17 years post-treatment) who achieved complete cytoreduction without recurrence demonstrate excellent health-related quality of life comparable to age-matched normal populations 5. This supports aggressive surgical management in appropriate candidates, as the treatment not only extends survival but maintains quality of life in long-term survivors.
Key Pitfalls to Avoid
- Do not rely on systemic chemotherapy alone—PMP is inherently chemoresistant, and systemic therapy has no established role outside clinical trials 2, 6
- Do not perform simple debulking without HIPEC—the combination is essential for optimal outcomes 2
- Do not use PET/CT for staging or surveillance—it is insensitive for mucinous disease 1
- Do not delay referral to specialized centers—complete cytoreduction rates and survival are operator-dependent, with better outcomes at high-volume centers 3, 6