EP549 - Differences in Recurrence Patterns and Factors Affecting Survival in Patients Undergoing HIPEC for Concurrent Peritoneal Metastases of Colorectal Cancer

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Purpose/Background: Postoperative recurrence is a common occurrence in patients who have undergone cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal metastases (PM) of colorectal cancer (CRC). Typically, 80-85% of patients experience recurrence within a period of 9-15 months. The aim of this multicenter study is to analyze the differences in recurrence patterns and factors affecting overall survival (OS) in patients with concurrent CRC PM.

Methods/Interventions: A retrospective analysis of data from five centers was conducted to identify risk factors for survival and recurrence in patients who underwent cytoreductive surgery and HIPEC for concurrent CRC PM between 1 January 2014 and 31 December 2020. The analysis employed the COX regression model.

Results/Outcomes: A total of 84 patients underwent cytoreductive surgery and HIPEC for concurrent CRC PM. The median follow-up period was 24.5 months (2-79), with 46 patients (54.8%) receiving preoperative chemotherapy and 72 patients (85.7%) receiving postoperative chemotherapy. The Peritoneal Cancer Index (PCI) values were less than 20 in 71 patients (84.5%) and greater than 20 in 13 patients (15.5%). The CCR0-1 was observed in 67 patients (79.8%), while the CCR2 was observed in 17 patients (20.2%). A total of 60 patients (71.4%) experienced a recurrence, with 26 cases (31%) confined to the peritoneum and 34 cases (40.5%) involving extraperitoneal spread. The median time to recurrence was 9 months (2-53), with 1-, 2-, and 3-year disease-free survival rates of 30%, 8.3%, and 5%, respectively. The median postoperative survival was 34 months (2-79), with one-, two-, and five-year OS rates of 88.5%, 64.4%, and 44.8%, respectively. When all patients were divided into three categories based on the presence of peritoneal recurrence alone, extraperitoneal recurrence, and both peritoneal and extraperitoneal recurrence, the median survival was 30.6 months, 34.4 months, and 15.8 months, respectively (P=0.013). The survival rates for patients with peritoneal and extraperitoneal recurrence were significantly worse in comparison to those with either peritoneal recurrence alone or extraperitoneal recurrence alone. Factors affecting OS included both peritoneal and extraperitoneal recurrence (HR 3.521 [1.380-8.984], P=0.045) and high PCI (HR 2.117 [1.049-4.2710], P=0.036). Regarding factors affecting recurrence, preoperative chemotherapy (HR 2.081 [1.203-3.601], P=0.009) and postoperative complications (HR 2.184 [1.190-4.006], P=0.012) were analyzed to enhance the probability of recurrence. For both peritoneal and extraperitoneal recurrence, obesity (HR 4.518 [1.441-14.166], P=0.010), postoperative chemotherapy (HR 0.284 [0.092-0.877], P=0.029), and high PCI (HR 7.391 [1.780-30.691], P=0.006) were identified as significant factors.

Conclusion/Discussion: Patients with both peritoneal and extraperitoneal recurrence exhibited a poorer prognosis and postoperative chemotherapy was associated with a reduced risk of these recurrences. Therefore, for patients with concurrent PM of CRC, if the PCI is not high, a treatment strategy that involves cytoreductive surgery and HIPEC followed by postoperative adjuvant chemotherapy is considered to be a superior approach.