P-115 Cytoreductive Surgery and HIPEC in the Treatment of Peritoneal Carcinomatosis: the Experience in a Tertiary University Hospital

The combination of surgical cytoreduction with HIPEC has been deeply explored as a locoregional approach to treat peritoneal carcinomatosis in gastrointestinal malignancies. Although many studies have been carried out, the role of HIPEC endures elusive. The data from published phase III trials have not shown benefits in overall survival (OS) or progression-free survival (PFS) rates. In this study, we aim to expose our experience in our center. We performed a retrospective descriptive analysis recruiting all patients diagnosed with peritoneal carcinomatosis from primary gastrointestinal tumors treated with cytoreductive surgery and HIPEC in Ramon y Cajal University Hospital Between 2015 and 2022, 49 patients with gastrointestinal tumors underwent cytoreduction with HIPEC in our center. 25 (51%) patients had colorectal cancer (CRC), 18 (36%) had mucinous neoplasms of the appendix, and 6 (12%) gastric cancer. Among CRC patients, 48% were left-sided colon, 36% right-sided colon and 16% were located at the rectum. All of them expressed mismatch repair proficiency and only 2 had BRAF mutation. The most common HIPEC regimen used during surgery was oxaliplatin with intravenous 5-FU simultaneously administered (55%), followed by mitomycin-C in monotherapy (30.6%). Combination of mitomycin with cisplatin was employed in 5 out 6 patients with gastric neoplasms (10% of all patients). Median PCI was 10 and complete resection was achieved in all patients. Postoperative complications appeared in 41 (83%) patients, being infections the most frequent (62% of patients), followed by cytopenias (34%) and paralytic ileus (25,5%). 26% required admission to the ICU. Presurgical chemotherapy was administrated in 40.8% of patients and 57% received it after surgery, mostly with combinations of fluoropyrimidines and oxaliplatin. 61% of patients progressed from the disease and among them, 70% relapsed at the peritoneum. 23% of the patients who relapsed exclusively at the peritoneum underwent new surgical resection. With a median follow-up of 35 months, median PFS of the population was 12 months and median OS was 54 months. OS was significantly lower in patients with primary gastric cancer (6 months) compared to CRC patients who showed a median OS of 44 months. Patients with mucinous neoplasm of the appendix had not reached median OS yet. Within the CRC patients group, the median OS for left-sided colon tumors was 12.5 months while for right-sided and rectum tumors was 54 and 63 months respectively. Patients who received mitomycin-C during HIPEC had a median OS of 46 months. When oxaliplatin was used medians OS was 63 months. Cytoreductive surgery combined with HIPEC is a feasible strategy for gastrointestinal neoplasms with peritoneal carcinomatosis. However, more clinical trials are warranted to unravel the role of HIPEC in these patients, especially in good prognosis malignancies such as mucinous neoplasm of the appendix or colorectal adenocarcinoma. For patients with a poor prognosis like those with gastric carcinoma, HIPEC with cytoreductive surgery should be carefully evaluated and employed in selected patients.