indications for cytoreductive surgery plus hipec in patients with colorectal cancer and peritoneal metastasis

Background: comprehensive treatment (compt) consisting of cytoreductive surgery (crs) with hyperthermic intraperitoneal chemotherapy (hipec) improves survival in selected patients with peritoneal metastasis (pm) from colorectal cancer (crc). the present study aimed to clarify clinicopathologic parameters that are indications for compt in crc patients with pm.methods: between 2006 and 2021, 447 patients were eligible for compt among 906 crc patients with pm. clinicopathologic parameters contributing to long-term survival and cure were analyzed.results: a log-rank test showed a significant survival difference for peritoneal cancer index (pci) (≤12 vs. ≥13, p<0.0001), completeness of cytoreduction (ccr) score (ccr-0 vs. ccr-1, p<0.0001), small bowel (sb)-pci (≤2 vs. ≥3), liver/lung metastasis (llm) (negative vs. positive, p=0.002), histologic type (differentiated type vs. signet ring cell (src) subtype, p=0.008), number of involved peritoneal sectors (≤6 vs. ≥7), hipec (done vs. not done) and postoperative complication (grades 0–2 vs. grades 3–5, p<0.0001). muti-variate analyses revealed that ccr score (ccr-0 vs. ccr-1, p<0.0001), sb-pci score (≤2 vs. ≥3, p<0.005), llm (negative vs. positive, p=0.002), and hipec (performed vs. not done) were independent prognostic factors. the incidence of postoperative grade 3–5 complications was 19.0% (85/447), and the mortality rate was 2.0% (9/447). one hundred seventy patients fulfilled the following clinicopathologic factors: pci≤12, sb-pci≤2, number of involved peritoneal sectors ≤6, no llm, differentiated histologic type, and ccr-0. the median survival time of these patients was 5.5 years, and five and ten-year survival rates were 57.8% and 24.6%, respectively. postoperative grade 3, 4, and 5 complications in these 170 patients occurred in 9 (5.3%), 15 (8.8%), and 1 (0.6%), respectively. cured patients were defined as those alive without recurrence more than five years after crs. all of the cured patients underwent ccr-0 resection. the pci and sb-pci of these 23 patients were ≤12 and ≤2, respectively.conclusion: among crc patients with pm, compt with ccr-0 resection is indicated for pci ≤12, sb-pci ≤2, number of involved peritoneal sectors ≤6, no llm, and differentiated histologic type.