What is the management approach for a patient with Pseudomyxoma peritonei (PMP)?

Management of Pseudomyxoma Peritonei

The definitive treatment for pseudomyxoma peritonei is complete cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), which achieves 5-year overall survival rates of 69-97% when complete tumor removal is accomplished. 1, 2

Initial Diagnostic Approach

• Obtain contrast-enhanced CT scan of the abdomen and pelvis to assess extent of peritoneal disease, identify the primary tumor source (typically appendiceal), and evaluate for distant metastases 3
• Measure tumor markers including CEA and CA 19-9 preoperatively, as these have significant prognostic value and utility for surveillance 3
• Document peritoneal cancer index (PCI) score during imaging review, as this quantifies disease burden and predicts resectability 1
• Obtain tissue diagnosis through biopsy when feasible to confirm mucinous histology and differentiate between disseminated peritoneal adenomucinosis (DPAM), peritoneal mucinous carcinomatosis (PMCA), or intermediate subtypes 1

Surgical Candidacy Assessment

• Refer all patients to specialized centers with experience in CRS and HIPEC, as expertise significantly impacts resection rates, morbidity, and mortality 4
• Evaluate performance status and medical operability including cardiac and pulmonary function, as extensive surgery requires patients who can tolerate prolonged procedures 1
• Assess resectability using MDCT radiological scoring systems, which demonstrate 94% sensitivity and 81% specificity for predicting complete cytoreduction 3
• Consider patients with PCI scores up to 39 as potential surgical candidates, as acceptable survival has been observed even with extensive disease when complete cytoreduction is achieved 1

Definitive Treatment Protocol

For resectable disease:

• Perform complete cytoreductive surgery with peritonectomy procedures to remove all visible tumor deposits from peritoneal surfaces 1, 2
• Administer HIPEC immediately following cytoreduction using either mitomycin C (3.3 mg/m²/L) plus cisplatin (25 mg/m²/L) at 42.5°C for 60 minutes via closed abdomen technique 2
• Alternative HIPEC regimen: early postoperative intraperitoneal chemotherapy (EPIC) using mitomycin C and 5-fluoruracil, which shows equivalent long-term outcomes to HIPEC 1

The choice between HIPEC and EPIC appears equivalent in efficacy, with 10-year overall survival of 69% and disease-free survival of 47% achieved with either approach 1.

Critical Surgical Pitfalls to Avoid

• Do not rely on repeated paracentesis for mucinous ascites management—this provides only temporary relief and should be replaced by early surgical debulking before disease becomes loculated or bowel becomes fixed 4
• Avoid incomplete cytoreduction, as optimal cytoreduction (removal of all visible disease) is the most critical determinant of survival 1, 2
• Do not dismiss patients with high PCI scores or aggressive histology from surgical consideration, as acceptable survival (5-year OS 23-82%) can be achieved even in these challenging cases when complete cytoreduction is possible 1, 3

Prognostic Factors

• Histopathological differentiation is the most important prognostic factor (p=0.001), with DPAM having superior outcomes compared to PMCA 1
• Female gender is associated with improved overall survival (p=0.045) 1
• Completeness of cytoreduction is paramount—92% of patients achieving optimal cytoreduction in specialized centers 2

Expected Outcomes and Complications

• Operative mortality should be <3% in experienced centers 2
• Major complications (Grade III) occur in approximately 18% of patients 2
• Grade II morbidity occurs in approximately 15% of patients 2
• Recurrence rates remain significant, with disease-free survival of 43-47% at 10 years, necessitating long-term surveillance 1

Management of Unresectable or Recurrent Disease

• Involve palliative care specialists early for symptom management when curative surgery is not feasible 4
• Apply standard cancer pain management principles with consideration of complex nociceptive and inflammatory components specific to peritoneal disease 4
• Consider low-dose oral morphine for dyspnea and associated anxiety in patients with respiratory compromise from diaphragmatic disease 4
• Systemic chemotherapy alone is not effective for PMP and should not be used as primary treatment 5
• Long-term nutritional support may improve quality of survival for select patients with recurrent disease 5

Surveillance Strategy

• Monitor tumor markers (CEA, CA 19-9) serially postoperatively to detect early recurrence 3
• Perform interval CT imaging to assess for disease recurrence, as many patients require multiple surgical interventions over time 6
• Maintain long-term follow-up, as the indolent nature of PMP means recurrences can occur years after initial treatment 6