Computed tomography-dominant surveillance strategies for colorectal cancer: Improving early detection of recurrence

Table 2 Risk-adapted surveillance strategy for postoperative stage I-III colorectal cancer patients

Risk category	Imaging (CT/MRI)	Colonoscopy	Biomarker testing (CEA)	Rationale
High-risk (e.g., stage III, MSS, positive biomarkers)	Every 6 months for years 1-3, annually for years 4-5 (low-dose protocols for patients < 50)	At 1 year post-surgery, then every 3 years if negative	Every 3 months for 3 years, then every 6 months	Higher recurrence risk justifies intensive imaging, balanced with low-dose CT to reduce radiation exposure[6,10,12]
Intermediate-Risk (e.g., stage II, MSS, negative biomarkers)	Annually for years 1-3, every 2 years for years 4-5 (MRI preferred for patients < 50)	At 1 year, then every 3-5 years if negative	Every 6 months for 3 years, then annually	Moderate risk warrants regular but less frequent imaging, with MRI to minimize radiation in younger patients[10,12]
Low-risk (e.g., stage I, MSI-H, negative biomarkers)	Every 2 years for years 1-5 (MRI or low-dose CT for patients < 50)	At 1 year, then every 5 years if negative	Annually for 5 years	Lower recurrence risk supports extended intervals, prioritizing radiation reduction[6,10,12]

MSS: Microsatellite stable; MSI-H: Microsatellite instability-high; CEA: Carcinoembryonic antigen; MRI: Magnetic resonance imaging; CT: Computed tomography.