EP554 - The Role of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy in the Treatment of Peritoneal Metastasis from Colon and Rectal Cancer

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Purpose/Background: Chemotherapy has been the standard of care for peritoneal metastasis from colorectal cancer. Klaver et al found no advantage to CRS-HIPEC over standard chemotherapy. CAIRO-2 showed median overall survival (OS) was decreased for patients with CRC and PC compared with patients without PC (15.2 months vs. 20.7 months). The PRODIGE 7 trial looked at the role of HIPEC in combination with CRS in treatment of colorectal cancer with peritoneal metastasis. They found no difference in median survival between HIPEC and non-HIPEC groups with the exception of patients with a Peritoneal Carcinomatosis Index (PCI) between 11-15. CRS-HIPEC has rapidly evolved to be the standard of care for PM from appendiceal cancer and mesothelioma, however. CRS-HIPEC has been used for other intra-abdominal adenocarcinomas such as ovarian and gastric carcinomas with PM with mixed success. Large volume HIPEC centers have begun to do CRS-HIPEC for selected patients with PM from CRC. Survival after CRS-HIPEC for other cancers is related to the disease burden as measured by the PCI. Based on experience with other cancers, it is postulated that there is a PCI beyond which CRS-HIPEC is ineffective and levels where CRS-HIPEC may be highly effective. Our study aims to review the experience and outcomes of CRS-HIPEC in the treatment of PM from CRC over 11 years in a large volume HIPEC center.

Methods/Interventions: This is a historical cohort study that was conducted by retrospective review of data. Data were obtained from the Ascension St. John HIPEC Clinical Registry for all patients who underwent HIPEC from January 1, 2011 through December 31, 2022. The collected data included patient demographics, clinical details regarding cancer diagnosis, surgical stage of disease, PCI score, surgical details, chemotherapeutic agents used, surgical complications, mortality, and patient outcomes.

Univariable analysis was done using Student’s t-test, analysis of variance followed by multiple pairwise comparisons using the Bonferroni correction of the p-value and chi-squared analysis. For non-normally distributed data, the Mann-Whitney and Kruskal-Wallis tests were used. Initial survival analysis was done using Kaplan Meier methods, for both survival and progression-free survival.

Multivariable analysis of survival was done with Cox proportional hazards models. Exploration of a possible PCI cut point was done using Receiver Operator Curves analysis and the chi-squared test to determine sensitivity, specificity, and positive and negative predictive values. All data wereanalyzed using SPSS v. 29.0 and a p-value less than 0.05 was taken to indicate statistical significance.

Results/Outcomes: We reviewed 107 patients from 2011 to 2022 with CRC and PM who underwent CRS and HIPEC; 98% of patients were infused with mitomycin C for 90 minutes at 42-43 degrees Celsius. Median survival for patients with PCI < 10 was 45 months, PCI 10-19 was 34 months, PCI 20-29 was 21 months, PCI 30+ was 19 months (p = 0.002). Three yr OS was 78.7% for PCI < 10, 68.4% for PCI 10-19, 50.0% for PCI 20-29, and 33.3% for PCI 30+ (p = 0.004). The five yr OS was 68.1% for PCI < 10, 60.5% for PCI 10-19, 30.0% for PCI 20-29, and 33.3% for PCI 30+ (p = 0.004).

Conclusion/Discussion: Our data set showed an overall survival benefit of CRS and HIPEC for patients with CRC with PM. This could be attributed to our protocol of using mitomycin C at 90-minute infusions at 42-43 degrees when compared with other studies such as the PRODIGE 7 trial which utilized oxaliplatin at 41.5 degrees for 30 minutes and showed no survival benefit of HIPEC.