Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy for Colorectal Peritoneal Metastases Offers 60% Five-Year Overall Survival for Low-Volume Disease

Introduction: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal early chemotherapy (HIPEC) has gained traction as a viable treatment option for patients with colorectal cancer peritoneal metastases (CRC-PM). Refinements have been made to patient selection and choice of HIPEC agent. We report outcomes with respect to peritoneal disease volume (peritoneal cancer index, PCI) and HIPEC agent for patients treated at the Western Australian Peritonectomy Service (WAPS) in the ten years from December 2013. Methods: A retrospective statistical analysis assessing the factors affecting survival outcomes of patients with CRC-PM who received CRS with HIPEC was performed, with particular focus on disease volume and HIPEC agent (Mitomycin C and Oxaliplatin). Results: 89 patients with CRC-PM were treated with CRS-HIPEC with a median overall survival (OS) of 58 months, 5-year OS of 48% and disease-free survival (DFS) of 20%. PCI <10 (n = 57) had OS and DFS of 60% and 29%, compared to 23% and 0% for PCI ≥ 10 (n = 32); HR = 2.9, p = 0.002. Three-year OS and DFS for treatment with Oxaliplatin HIPEC (n = 40) were 61% and 41%, which was not significantly different from 71% and 34% with Mitomycin C HIPEC (n = 49); HR = 1.5, p = 0.3. Conclusions: CRS/HIPEC should continue to evolve into the standard of care for carefully selected patients with CRC-PM as almost half of all selected patients survive to at least five years; in particular patients with low-volume disease (PCI < 10) can benefit greatly with a 60% five-year OS and 29% five-year DFS with low morbidity. The choice of HIPEC agent, Oxaliplatin or Mitomycin C, remains uncertain.