Colorectal Cancer — Proceedings from a Session Held in Conjunction with the 2026 ASCO Annual Meeting

Neoadjuvant PD-1 blockade has transformed the management of MSI-high/dMMR locally advanced rectal cancer, yielding high clinical complete response rates and offering a potential alternative to traditional chemoradiation and surgery. In colon cancer, molecular residual disease (MRD) testing through ctDNA serves as a critical prognostic tool, allowing for risk-stratified de-escalation or escalation of adjuvant chemotherapy. While observational data confirm the validity of MRD assays, ongoing prospective trials aim to define their role in clinical decision-making. Metastatic colorectal cancer management continues to shift toward biomarker-driven sub-classification, incorporating targeted therapies for BRAF, HER2, and RAS mutations. Emerging combinations, such as zanzalintinib plus atezolizumab, demonstrate potential in refractory disease, though clinicians remain cautious regarding toxicity profiles and the need for more robust biomarkers to guide treatment selection, particularly in patients with liver metastases.