Peritoneal cancer index (PCI) based patient selecting strategy for complete cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy in gastric cancer with peritoneal metastasis: A single-center retrospective analysis of 125 patients.

Objective: The role of cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) in gastric cancer with peritoneal metastasis (GCPM) is still controversial, mainly due to the limited survival benefit and uncertain patient selection. This study aims to construct a selecting strategy in GCPM for CRS + HIPEC.

Methods: From a prospective established database, 125 patients were enrolled. All these patients were pathologically confirmed as GCPM and treated with CRS + HIPEC with or without preoperative or postoperative chemotherapy. The clinical documents and follow-up results were collected and analyzed with the primary endpoint of overall survival (OS) and the secondary endpoint of perioperative serious adverse events (SAEs).

Results: The median OS of 125 GCPM patients treated with CRS + HIPEC was 10.7 months, with 1-, 2-, 3-, and 5-year survival rates of 43.8%, 24.7%, 18.6%, and 15.7%, respectively. The multivariate analysis identified completeness of cytoreduction (CC), SAEs, HIPEC drugs, and adjuvant chemotherapy as independent prognostic factors on OS. The median OS was 30.0 (95%CI: 16.8-43.3) months in CC-0 group, significantly better than 7.3 (95%CI: 5.8-8.8) months in CC1-3 group (P < 0.001). The median OS showed no significant difference among CC-1 (8.5, 95%CI: 6.7-10.2, months), CC-2 (5.6, 95%CI: 3.0-8.2, months) and CC-3 (6.5, 95%CI: 5.2-7.7, months) groups (P > 0.05 for all pairwise comparations). The nomogram based on peritoneal metastasis timing, preoperative tumor marker (TM), and peritoneal cancer index (PCI), with AUC of 0.985, showed a good accuracy and consistency between actual observation and prediction of the probability of complete CRS. The cutoffs of PCI were 16 for synchronous GCPM with normal TM, 12 for synchronous GCPM with abnormal TM, 10 for metachronous GCPM with normal TM, and 5 for metachronous GCPM with abnormal TM, setting the probability to achieve complete CRS as 50%.

Conclusions: Only complete CRS + HIPEC (CC-0) could improve survival for high selected GCPM patients with acceptable safety. An incomplete CRS (CC1-3) should be avoided for GCPM patients. Synchronous GCPM with PCI ≤16 and normal TM, synchronous GCPM with PCI ≤12 and abnormal TM, metachronous GCPM with PCI ≤10 and normal TM, or metachronous GCPM with PCI ≤5 and abnormal TM maybe potential indications for complete CRS + HIPEC treatment.