Immunotherapy Plus Surgery Improves Survival in Microsatellite Instability-High Colon Cancer with Isolated Peritoneal...

Area of Science:

• Oncology
• Gastroenterology
• Immunotherapy

Background:

• Microsatellite instability-high (MSI-H) colon cancer with isolated peritoneal metastases (iPM) is a distinct subset with poor prognosis.
• Limited evidence guides treatment for MSI-H colon cancer with iPM.
• The immunogenic nature of MSI-H tumors warrants investigation into immunotherapy efficacy.

Purpose of the Study:

• To evaluate the association of immunotherapy, chemotherapy, and surgery with survival outcomes in MSI-H colon cancer with iPM.
• To determine the optimal treatment strategy for this specific patient population.

Main Methods:

• Utilized the National Cancer Database (2016-2021) for patient identification.
• Stratified patients by systemic therapy (immunotherapy, chemotherapy, combination) and surgical resection.
• Employed Kaplan-Meier and multivariable Cox regression for overall survival (OS) analysis.

Main Results:

• Immunotherapy significantly improved median OS compared to chemotherapy (33 vs. 18 months).
• Immunotherapy was independently associated with improved survival (HR: 0.46).
• Surgical resection, with or without metastatectomy, improved survival; combination with immunotherapy yielded the greatest benefit.

Conclusions:

• Immunotherapy significantly improves survival in MSI-H colon cancer with iPM compared to chemotherapy.
• A multimodal approach combining surgery and immunotherapy offers the greatest survival benefit.
• Real-world evidence supports integrating immunotherapy and surgery for this distinct patient group.