Endoscopic follow-up in colorectal cancer: Comparisons and critical issues across different guidelines

Table 4 Non-surgical management strategies in colorectal cancer

Setting	Key evidence	Criteria to avoid surgery	Recommended follow-up	Key recommendations
Rectal cancer - “watch and wait” strategy	Large international experience; organ preservation possible without compromising oncologic outcomes	cCR after neoadjuvant therapy. Assessment in expert centers. Ability to perform salvage surgery if needed	Clinical visit + digital rectal exam every 3-4 months. Endoscopy every 3-4 months. Pelvic MRI every 6 months. CEA monitoring. Annual chest-abdomen CT	Use only after strict confirmation of cCR. Intensive surveillance for at least 2-3 years. Requires multidisciplinary management
Locally advanced rectal cancer treated with TNT	TNT increases cCR rates and allows organ preservation (e.g., OPRA: Approximately 50% of complete responders avoid surgery)	Clinical complete response after TNT (chemo + chemoradiotherapy). Patient commitment to intensive follow-up	Same as above: Intensive surveillance concentrated in first 2-3 years	Real possibility to avoid TME. Early detection of recurrence is crucial for successful salvage
MSI-H/dMMR tumors (rectum and colon) treated with immunotherapy	Early studies (e.g., Cercek): All patients achieved clinical complete response without surgery after anti-PD1 therapy	Confirmed MSI-H/dMMR. Complete clinical/radiologic response after immunotherapy	Not yet standardized; likely prolonged intensive surveillance. Possible integration of ctDNA	Monitoring strategy still evolving. Watch for late recurrences or resistance. Should be managed only in highly experienced centers
Colon cancer (non-MSI-H/dMMR)	Surgery remains the standard of care; conservative management only in extremely selected cases	Rare complete response, generally only in MSI-H tumors treated with immunotherapy	Standard oncologic follow-up	Avoid non-surgical strategies outside specialized protocols or exceptional cases

cCR: Clinical complete response; CEA: Carcinoembryonic antigen; MRI: Magnetic resonance imaging; CT: Computed tomography; TNT: Total neoadjuvant therapy; TME: Total mesorectal excision; MSI-H: Microsatellite instability-high; dMMR: Deficient mismatch repair; ctDNA: Circulating tumor DNA; PD1: Programmed death 1.