PSM
Rhami Khorfan, MD MS
CGSO Fellow
Loma Linda University, United States
Rhami Khorfan, MD MS
CGSO Fellow
Loma Linda University, United States
Rhami Khorfan, MD MS
CGSO Fellow
Loma Linda University, United States
.jpg "Shaina Sedighim, MD photo")
Shaina Sedighim, MD
Resident Physician
University of California, Irvine, Department of Surgery
Irvine, California, United States
David Caba-Molina, MD MS MPH
Assistant Professor
Loma Linda University, United States
Thuy Tran, MD
Assistant Professor
University of California, Irvine
Orange, California, United States
Maheswari Senthil, MD (she/her/hers)
Chief of Surgical Oncology
University of California, Irvine
Irvine, California, United States
Michael P. O’Leary, MD (he/him/his)
Attending Surgeon
Loma Linda University, Department of Surgery
Loma Linda, California, United States
.jpg "Oliver Eng, MD (he/him/his) photo")
Oliver Eng, MD (he/him/his)
Associate Professor of Surgery
University of California, Irvine
Orange, California, United States
KEYNOTE-177 demonstrated that immune checkpoint inhibitor therapy led to significantly improved progression-free survival compared to chemotherapy in MSI-high metastatic colorectal cancer. Colorectal cancer with peritoneal metastases (CRPM) has a poorer prognosis than other metastatic sites, and the role of immunotherapy in MSI-high CRPM patients specifically is not well defined. We sought to evaluate trends in utilization of immunotherapy for MSI-high CRPM, factors associated with use, and overall survival (OS).
Methods:
Patients with CRPM and confirmed MSI testing were identified in the National Cancer Database (2016-2020). Immunotherapy as first course treatment was quantified by year and associated patient/hospital factors were evaluated. OS was compared for patients treated with immunotherapy vs chemotherapy, cytoreductive surgery (CRS), and immunotherapy plus CRS.
Results:
Among 15,322 CRPM patients, 7,072 (46.2%) patients had confirmed MSI testing, with 819 (11.6%) confirmed MSI-high patients. Testing increased from 25.5% in 2016 to 61.8% in 2020. 98 MSI-high patients received immunotherapy alone (12.3%), which increased significantly from 0% in 2016 to 19.1% in 2020 (p< 0.01). On multivariable analysis, only co-morbidity index (OR 4.31 [1.76-10.55] for Charlson score 2 vs 0, p< 0.01) and academic hospital (OR 2.51 [1.37-4.60], p< 0.01) were significantly associated with use of immunotherapy. Two-year OS with immunotherapy vs chemotherapy was 64.2% vs 54.1% (p< 0.05). In MSI-high patients who underwent CRS and some form of systemic therapy (N=96), two-year OS was 68.4%. When looking specifically at patients who underwent the combination of immunotherapy and CRS (N=12) versus immunotherapy alone (N=45), two-year OS was 80.0% compared to 60.0% (p=0.14).
Conclusions:
Immunotherapy was associated with significantly improved survival compared to chemotherapy for MSI-high CRPM patients. Two-year OS in MSI-high CRPM patients who undergo systemic therapy and CRS was 68.4%. Despite its role in guiding treatment, MSI testing remains low for this cohort of metastatic colorectal patients for whom universal testing is advocated.