Does hipec improve outcomes in gastric cancer patients treated with perioperative chemotherapy and radical surgery? A propensity‐score matched analysis

Abstract Background Hyperthermic intraperitoneal chemotherapy (HIPEC) has been associated with improved survival when compared with surgery alone for non‐metastatic gastric cancer patients in randomized trials and meta‐analyses. However, little evidence is available regarding the use of HIPEC in nonmetastatic patients who are treated with perioperative chemotherapy and radical surgery. The aim of this study was to investigate the putative survival benefit of HIPEC in the subgroup of gastric cancer patients treated with perioperative chemotherapy and surgery. Patients and Methods This was a retrospective cohort study that included gastroesophageal junction and gastric cancer patients who were treated with perioperative chemotherapy and curative resection in a single cancer center in the period between 2006 and 2017. In this time period, younger patients with diffuse‐type tumors and serosa invasion or positive lymph node disease were often offered an adjuvant HIPEC protocol. This study compared the survival outcomes of these patients to the ones of those who received only perioperative chemotherapy and resection. A 2:1 propensity‐score matched analysis for the two groups was also performed, and variables used were postchemotherapy T (ypT) and N (ypN) stages, histology and tumor site. Results The study population comprised 269 subjects, 241 treated with chemotherapy and surgery and 28 who also received HIPEC. The mean age was 59 years old (standard deviation: 12.2) and 60% of all individuals were male. A total gastrectomy was performed in 137 patients and a distal resection in 132, with a D2‐lymphadenectomy in 97.4% of the sample. Overall 60‐day morbidity and mortality rates were 35.3% and 3.3%, respectively. In the HIPEC group, patients were younger, and more frequently had American Society of Anesthesiologists (ASA) 1 to 2 classification, tumors located in the gastric body, had diffuse histology, and ypN+ disease. Overall survival (OS; 5 years) results in the HIPEC and no HIPEC group were 59.5% vs 68.7% ( P = .453), and disease‐free survival (DFS) ones were 49.5% and 65.8% ( P = .060), respectively. In the multivariable Cox regression model, ypT and ypN were independent overall and DFS predictors; also, ASA 3 to 4 classification and diffuse histology were associated with worse OS. In the matched analysis, HIPEC did not improve either overall (53.5% vs 59.5%; P = .517) or DFS (50.0% vs 49.5%; P = .993). Conclusion Treatment with HIPEC in patients who received perioperative chemotherapy and a D2‐resection did not improve survival outcomes. Both ypT and ypN stages remained as the most important survival predictors in this cohort.