EP2009 - Mitomycin C-Based HIPEC for Colorectal Peritoneal Metastases: A High-Volume Southeast Asian Experience from King Chulalongkorn Memorial Hospital

Purpose/Background: While oxaliplatin is widely used in modern cytoreductive surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) trials, mitomycin C remains a relevant agent due to its lower cost and longer peritoneal exposure time. However, real-world data on its use for colorectal cancer with peritoneal metastases (CRC-PM), particularly in Southeast Asia, are limited. This study aims to evaluate the perioperative and oncologic outcomes for patients with CRC-PM who underwent CRS and a mitomycin C-based HIPEC protocol in a high-volume tertiary center.

Methods/Interventions: We retrospectively reviewed the data of 90 patients with CRC-PM who were scheduled for CRS followed by HIPEC at our institute, King Chulalongkorn Memorial Hospital. Of these, 84 patients received HIPEC with mitomycin C at 35-42°C for 90 minutes following CRS. The remaining 6 patients who received CRS alone were excluded. Variables analyzed included patient demographics, Peritoneal Cancer Index (PCI) score, completeness of cytoreduction (CC) score, operative metrics, postoperative complications (Clavien-Dindo classification), and survival outcomes. Kaplan-Meier analysis and the log-rank test were used to assess recurrence-free survival (RFS) and overall survival (OS). A p-value < 0.05 was considered statistically significant.

Results/Outcomes: For the 84 patients who underwent CRS with HIPEC, the median age was 63.0 years, and 42.9% were male. 36.9% of patients had synchronous peritoneal metastasis. The median PCI score was 5.0 (IQR 3.00-8.75). Complete cytoreduction (CC-0/1) was achieved in 98.7% of cases. Postoperative complications occurred in 22.6% of patients, with major complications (Clavien-Dindo grade ≥3) recorded in 14.3% of cases. The mean length of hospital stay was 14.58 days, and there was no 30-day mortality.

Regarding oncological outcomes, cancer recurrence was observed in 61.9% of patients. The median recurrence-free survival was 20.0 months (95% CI, 14.60-25.40), with 1-year, 3-year, and 5-year RFS rates of 66.1%, 26.5 and 21.7%, respectively. Among the patients with recurrence, 40 developed extraperitoneal metastases (76.9%). The median overall survival was 33.0 months (95% CI, 28.80-37.20). The 1-year, 3-year, and 5-year overall survival rates were 72.6%, 21.4%, and 15.5%, respectively.

Conclusion/Discussion: In this single-center experience, mitomycin C-based HIPEC following CRS is a feasible procedure for selected patients with CRC-PM, offering durable disease control with acceptable, though increased, morbidity compared to CRS alone. The Peritoneal Cancer Index was the most significant predictor of survival, underscoring that meticulous patient selection is critical to achieving favorable long-term outcomes. These findings highlight mitomycin C as a viable and resource-conscious alternative in real-world practice, particularly in settings where other regimens may be cost-prohibitive. Further prospective comparison is warranted to confirm these outcomes.

Kaplan-Meier curve for recurrence-free survival
Kaplan-Meier curve shows recurrence-free survival for patients who were treated with mitomycin C-based HIPEC. The 1-year, 3-year, and 5-year RFS rates of 66.1%, 26.5 and 21.7%, respectively.
Kaplan-Meier curve for overall survival
Kaplan-Meier curve shows overall survival for patients who were treated with mitomycin C-based HIPEC. The 1-year, 3-year, and 5-year overall survival rates were 72.6%, 21.4%, and 15.5%, respectively.