Outcomes for Gastrectomy During Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Non-Gastric Primaries: A 30-Year Experience.

Introduction: Cytoreductive surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) can improve survival for patients with peritoneal surface malignancy. Completeness of cytoreduction correlates with prognosis. The role of gastrectomy in these patients is not well described.

Methods: 1868 patients who underwent CRS+HIPEC for non-gastric primary between 1991-2024 were analyzed from a prospective database. Patients were stratified by gastrectomy extent and their outcomes compared with no-gastrectomy patients. Continuous variables are presented as mean (SD), categorical variables as N (%) and values considered statistically significant at < 0.05.

Results: There were no differences in baseline demographics between the gastrectomy and no-gastrectomy groups. There were 23 major, 45 distal, and 77 wedge gastrectomies (n=145, 7.76%). Appendiceal was the most common neoplasm in the gastrectomy groups (major: 96%, distal: 91%, wedge: 68%, no gastrectomy: 53%). Gastrectomy patients had higher median PCI [major: 27(7.0), distal: 24(7.0), wedge: 19(10.3), no-gastrectomy: 14(9.5); p<0.001], R2 resection (major: 96%, distal: 89%, wedge: 60%, no-gastrectomy: 45%; p<0.001), severe complications (major: 30%, distal: 27%, wedge: 19%, no-gastrectomy: 12%; p<0.001), LOS [major: 24(15.2) , distal: 23(25.7), wedge: 18(22.2), no-gastrectomy: 12 (12.5) days; p<0.001], and 30-day mortality (major: 17%, distal: 11%, wedge: 10%, no-gastrectomy: 5%; p<0.001). There was no difference in 30-day readmission or recurrence. On multivariate analysis, gastrectomy was not independently associated with overall survival (OS) (p=0.18).

Conclusion: 8% of patients who underwent CRS+HIPEC for non-gastric primaries underwent gastrectomy. Gastrectomy patients were more likely to have higher PCI and incomplete resections with increased complications and mortality. PCI, resection status, LN's, tumor grade, and primary site, but not gastrectomy type, are significantly associated with OS.