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

Table 1 Comprehensive tests for oncologic follow-up based on National Comprehensive Cancer Network, European Society for Medical Oncology and Italian Association of Medical Oncology guidelines

Exam/assessment	Post-surgical patients (colon/rectum)
Clinical visit + medical history + physical examination	Every 3-6 months for 3 years, then every 6-12 months up to 5 years
Serum CEA	Every 3-6 months for 2 years, then every 6 months up to 5 years (only if candidates for curative surgery)
Colonoscopy	At 1 year after surgery, then at 3 years, then every 5 years (more frequently if advanced polyps or incomplete resections)
Rectoscopy/flexible sigmoidoscopy	In patients with rectal resection, every 6-12 months for 2-3 years
Pelvic MRI	Not routine; reserved for high-risk rectal tumors
Chest-abdomen-pelvis CT scan	Every 6-12 months for 3 years, then annually up to 5 years (for high-risk stage II and stage III)
Emerging biomarkers (ctDNA)	Not routinely recommended; use in clinical trials

CEA: Carcinoembryonic antigen; MRI: Magnetic resonance imaging; CT: Computed tomography; ctDNA: Circulating tumor DNA.

Table 2 Different surveillance interval recommendations for conventional adenomas in Western guideline

Colonoscopy findings	ESGE	BSG/ACPGBI/PHE	USMSTF
1-2 tubular adenomas < 10 mm	Return to screening	Return to screening	7-10 years
3-4 tubular adenomas < 10 mm	Return to screening	Return to screening	3-5 years
5-10 tubular adenomas < 10 mm	3 years	3 years	3 years
≥ 10 adenomas	Genetic counseling	Refer to BSG hereditary CRC guidelines1	1 year and consider genetic counseling
Adenoma with villous histology < 10 mm	Return to screening	Return to screening	3 years
Adenomas ≥ 10 mm	3 years	3 years	3 years
Adenoma with high-grade dysplasia	3 years	3 years	3 years
Piecemeal resection of adenoma ≥ 20 mm	3-6 months	2-6 months	6 months

¹If > 60 years old and lifetime history > 10 adenomas removed or if ≥ 60 years old and lifetime total ≥ 20 adenomas or ≥ 10 and family history colorectal cancer.

ESGE: European Society of Gastrointestinal Endoscopy; BSG: British Society of Gastroenterology; ACPGBI: Association of Coloproctology of Great Britain and Ireland; PHE: Public Health England; USMSTF: United States Multi-Society Task Force.

Table 3 Different surveillance interval recommendations for sessile serrated lesions in Western guideline

Colonoscopy findings	ESGE	BSG/ACPGBI/PHE	USMSTF
1-2 SSP < 10 mm	Return to screening	Return to screening	5-10 years
3-4 SSP < 10 mm	Return to screening	Return to screening	3-5 years
≥ 5 SSP < 10 mm	3 years	3 years	3 years
SSP ≥ 10 mm	3 years	3 years	3 years
SSP with dysplasia	3 years	3 years	3 years

SSP: Sessile serrated polyps; ESGE: European Society of Gastrointestinal Endoscopy; BSG: British Society of Gastroenterology; ACPGBI: Association of Coloproctology of Great Britain and Ireland; PHE: Public Health England; USMSTF: United States Multi-Society Task Force.

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.