This protocol addresses a specific subset of colon adenocarcinoma characterised by mismatch repair deficiency (dMMR) or high microsatellite instability (MSI-H), or by a POLE/POLD1 mutation conferring an ultra-hypermutated phenotype — in the setting where disease is non-metastatic but is either locally unresectable or the patient is medically inoperable.
Colon adenocarcinoma confirmed as dMMR/MSI-H or POLE/POLD1 mutation with ultra-hypermutated phenotype (e.g., TMB >50 mut/Mb), non-metastatic stage, that is locally unresectable or where surgery is medically not feasible.
Checkpoint inhibitor immunotherapy is the preferred approach in this biomarker-selected setting. Locoregional strategies may additionally be considered in the perioperative context — the complete structured regimen, including sequencing and all options, is available via the full protocol.