Treatment of Peritoneal Carcinomatosis of Colorectal Origin

Patient Selection and Treatment Outcomes

The American Society of Clinical Oncology (ASCO) 2023 guideline reports that cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) reduces the risk of death with a hazard ratio of 0.55 (95% CI, 0.32-0.95), translating to 181 fewer deaths per 1,000 patients at 24 months compared to systemic chemotherapy alone, in patients with peritoneal carcinomatosis of colorectal origin without distant metastases 1, 2
The European Society for Medical Oncology (ESMO) 2012 guidelines considered CRS + HIPEC as "experimental" and recommended treatment within clinical trials, highlighting the evolving nature of evidence for this treatment approach 3, 4
Patients with limited peritoneal disease (Peritoneal Cancer Index (PCI) < 20), no extraperitoneal metastases, good performance status, and limited small bowel disease are considered candidates for CRS + HIPEC, with a possibility of complete cytoreduction 3, 4
The ASCO 2023 guideline suggests that the addition of HIPEC to CRS may not provide a significant survival benefit in patients with complete cytoreduction, with a hazard ratio of 1.00 (95% CI, 0.63-1.58) and increased toxicity 1, 2

Systemic chemotherapy is the standard treatment for patients not eligible for CRS + HIPEC, with regimens based on fluoropyrimidines combined with oxaliplatin or irinotecan 1, 2
The addition of biological therapy (anti-EGFR or anti-VEGF) to chemotherapy is recommended based on the primary tumor's lateralization and RAS mutation status, with anti-EGFR therapy reducing mortality in left-sided RAS wild-type tumors 1, 5

Initial evaluation includes complete staging with CT scans, determination of PCI, assessment of performance status, and molecular analysis (RAS, tumor lateralization) 3, 4, 1, 5
Patients with PCI < 20, no extraperitoneal metastases, and good performance status are referred to specialized centers for CRS + HIPEC evaluation, with consideration of complete cytoreduction feasibility 3, 4
Patients with PCI ≥ 20, extraperitoneal metastases, or anticipated incomplete cytoreduction are treated with systemic chemotherapy as primary treatment, with regimen selection based on tumor lateralization and RAS status 1, 3, 4, 5