HIPEC for metastatic gastric cancer: Moving the needle towards 3-year survival

Introduction: Prior work has established hyperthermic intraperitoneal chemotherapy (HIPEC) administration as a safe treatment option for select patients with gastric adenocarcinoma and carcinomatosis. However, identifying patients who will maximally benefit from HIPEC remains unclear. This study assessed a single-institution experience with HIPEC for metastatic gastric cancer to identify variables associated with improved survival. Methods: A database of patients treated for metastatic gastric adenocarcinoma at MD Anderson Cancer Center from 2013 to 2022 was queried for patients undergoing HIPEC as part of their treatment regimen. Patients were stratified by overall survival (OS)≥36 months or <36 months and assessed along demographic and clinicopathologic variables to identify factors associated with OS ≥ 36 months. Results: Among 104 patients, 1,2, and 3-year OS from diagnosis was 89 %,44 %, and 18 %. Patients with OS ≥ 36 months were more likely to have moderately differentiated tumors, positive cytology only (i.e. no visible carcinomatosis), and lower peritoneal cancer index (PCI) than those with OS < 36 months (p = 0.002, p = 0.01, p = 0.001,respectively). Groups did not otherwise differ with respect to demographic parameters or treatment or pathologic details. Among patients who underwent gastrectomy, those with OS < 36 months had higher pathologic T and N category (p = 0.003 and p = 0.02, respectively). Postoperative mortality was zero in both groups among patients undergoing gastrectomy. Conclusions: HIPEC may provide more durable survival benefit among patients with metastatic gastric cancer with moderately differentiated disease, low PCI, and positive cytology alone. Additionally, among patients who undergo gastrectomy, higher final pathologic T and N category are associated with worse survival. Trials are needed to compare 3-year OS rates in patients treated with HIPEC versus systemic therapy alone.