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After an operation to cure bowel cancer, you will usually have regular blood tests (CEA) and CT scans for the first 3 years, and a colonoscopy about a year after surgery. The aim is to find a return early enough to operate again. How often you are tested differs between countries, and the large trials found that testing more often does not, on average, help people live longer.
NICE NG151 offers follow-up for the first 3 years after potentially curative surgery for non-metastatic colorectal cancer, with serum carcinoembryonic antigen (CEA) and CT of the chest, abdomen and pelvis, and does not set a frequency. The American Cancer Society (2015) endorses the NCCN schedule for stages I to III: history and examination and CEA every 3 to 6 months for 2 years, then every 6 months to 5 years; CT every 12 months; colonoscopy at 1 year. ASCO (2013) gives CEA every 3 to 6 months for 5 years and CT annually for 3 years in most cases. Colonoscopy is at 1 year after surgery in all these sources; the next is after 3 more years (BSG/ACPGBI 2020, NCCN) or 5 years (ASCO). PET-CT is not a surveillance test.
The evidence for intensity is weak: the 2019 Cochrane review of 19 randomised trials (13,216 people) found that intensive follow-up made little or no difference to overall survival (hazard ratio 0.91, high-quality evidence), although it nearly doubled salvage surgery with curative intent. Surveillance is only for people fit for further surgery or treatment, and colonoscopic surveillance stops in general at about 75 or with a life expectancy under 10 years (BSG/ACPGBI). People who had sphincter-preserving surgery should be told about low anterior resection syndrome and how to get help (NICE).
Why: Tests only help if finding a return would lead to treatment; someone who could not have further surgery or treatment gains nothing from them.
“Testing should only be performed in patients in whom the results will change treatment decisions.”
American Cancer Society, CA: A Cancer Journal for Clinicians 2015
Why: Most returns happen in the first few years, and finding them with CEA and liver imaging makes them more likely to be operable.
“For people who have had potentially curative surgical treatment for non-metastatic colorectal cancer, offer follow-up for detection of local recurrence and distant metastases for the first 3 years. Follow-up should include serum carcinoembryonic antigen (CEA) and CT scan of the chest, abdomen and pelvis.”
Why: This is the frequency in the American schedules; people at higher risk of return are seen at the more frequent end.
“Recommendation 4: Carcinoembryonic antigen (CEA) testing should be conducted every 3–6 months for the first 2 years and every 6 months for years 3–5 for those with T2 or greater lesions. CEA is not recommended after 5 years.”
American Cancer Society, CA: A Cancer Journal for Clinicians 2015 · 2A
Why: Yearly scans find spread to the liver or lungs while it may still be removable.
“In contrast to the NCCN recommendations, ASCO recommends CT scans of the abdomen and chest annually for only 3 years for CRC survivors.”
American Cancer Society, CA: A Cancer Journal for Clinicians 2015 · 2A
Why: It finds polyps or a second cancer that were missed or have grown since, and clears the bowel.
“We recommend that patients who have undergone a potentially curative CRC resection should have a clearance colonoscopy within a year of their diagnosis”
BSG, ACPGBI and PHE, Gut 2020 · GRADE of evidence: low; strength of recommendation: strong
Why: Polyps take years to turn into cancer, so a clear colonoscopy buys time before the next.
“We recommend that once a clearance colonoscopy has been performed in the postoperative period in patients who have had a CRC resection, their next surveillance should be performed after an interval of 3 years.”
BSG, ACPGBI and PHE, Gut 2020 · GRADE of evidence: low; strength of recommendation: strong
Why: They add cost and false alarms without finding treatable returns earlier.
“After five years, routine CEA monitoring is not recommended After five years, routine CT scans are not recommended Routine use of PET/CT is not recommended for any stage”
American Cancer Society, CA: A Cancer Journal for Clinicians 2015 · 2A
Why: A new polyp takes many years to become a cancer that causes harm, so late surveillance rarely helps.
“surveillance should only be performed in people whose life-expectancy is greater than 10 years, and in general not in people older than about 75 years.”
BSG, ACPGBI and PHE, Gut 2020 · GRADE of evidence: low; strength of recommendation: weak
Why: Bowel urgency, frequency and leakage after rectal surgery are common and treatable, and may start after discharge.
“Give information on low anterior resection syndrome (LARS) to people who will potentially have sphincter-preserving surgery.”
Why: Follow-up is often shared between hospital and primary care, and missed tests happen when nobody knows whose job they are.
“A treatment plan from the specialist should have clear directions on appropriate follow-up by a nonspecialist.”
How care is usually carried out, read from the guidelines and standards cited. Your own team's protocol and their judgement come first; this page is for understanding it, not for doing it yourself.
All sources agree on surveillance with CEA and CT for the first years after curative treatment and a colonoscopy within a year; they differ on frequency and length. NICE NG151 (2020) sets 3 years with CEA and CT and no frequency; ASCO (2013) sets CEA every 3 to 6 months for 5 years, CT annually for 3 years, and colonoscopy at 1 year then every 5 years; the American Cancer Society (2015) endorses NCCN's longer schedule, with CT every 12 months up to 5 years for higher-risk stage I to III disease and colonoscopy at 1 and 3 years; BSG/ACPGBI (2020) set colonoscopy at 1 year and 3 years after that. The best-supported reading of the trials (Cochrane 2019, 19 randomised trials, high-quality evidence) is that intensive follow-up finds more returns that can be operated on but makes little or no difference to overall survival, which supports the shorter, lighter end of these schedules for most people. ESMO's 2020 colon and 2025 rectal guidelines could not be read.
NICE 2020 · NICE 2020 · American Cancer Society, CA: A Cancer Journal for Clinicians 2015 · ASCO, Journal of Clinical Oncology 2013 · BSG, ACPGBI and PHE, Gut 2020 · Cochrane Database of Systematic Reviews 2019 · ESMO, Annals of Oncology 2020 · ESMO, Annals of Oncology 2025
Where it differs: CT every 12 months for stages I to III in years 1 and 2 and up to 5 years for higher-risk and stage III disease; colonoscopy at 1 year, at 3 years and then every 5 years; proctoscopy every 6 months for rectal cancer; and, for stage IV with no evidence of disease, CT every 3 to 6 months in years 1 and 2.
Evidence: Level of evidence 2A for the whole table, as printed by the ACS; the ACS notes that ASCO does not recommend the 3-year colonoscopy.
American Cancer Society, CA: A Cancer Journal for Clinicians 2015
Where it differs: History, examination and CEA every 3 to 6 months for 5 years; CT of abdomen and chest annually for 3 years in most cases; colonoscopy 1 year after surgery and then every 5 years, guided by the previous one.
Evidence: An endorsement of a guideline built on the same trials; read as an abstract.
Where it differs: Sets the length (the first 3 years) and the tests (CEA and CT of chest, abdomen and pelvis) and leaves the frequency to local practice; leaves colonoscopic surveillance to the BSG and ACPGBI guidance.
Evidence: NICE's committee found that recurrence was more likely to be resectable with regular follow-up including CEA and liver imaging, and found no evidence to change its 2011 recommendation.
Where it differs: Schedules history and examination and abdominal ultrasound at intervals, with CT at a single point and the choice between CT and ultrasound made individually; re-assesses CEA after curative treatment where it was raised before; colonoscopy within 6 months of surgery if the bowel was not fully examined before; length of follow-up, 3 or 5 years, decided individually.
Evidence: The 2025 English-language summary of the German S3 guideline cites the same Cochrane review and an earlier meta-analysis that did find a benefit of intensive follow-up. Its table of months lost its column positions in the text read, so the exact months for each test are not given here.
Deutsches Ärzteblatt International (summary of the German S3 guideline) 2025
Not every survivor needs to see an oncologist every six months for years. Sort people by recurrence risk, send low-risk survivors back to their family doctor with a clear plan, and guarantee rapid return if something changes.
| Recommendation | Grade, as printed | Source |
|---|---|---|
| Surveillance colonoscopy on a risk-based schedule “Recommendation 2: CRC survivors should receive surveillance colonoscopy according to a schedule based on based on risk. Level of Evidence = 2A” | 2A | American Cancer Society, CA: A Cancer Journal for Clinicians 2015 |
| History and examination every 3 to 6 months for 2 years, every 6 months to 5 years, then annually “Recommendation 3: CRC survivors should receive a history and physical every 3–6 months in the first 2 years and every 6 months in years 3–5, and annually after 5 years.” | 2A | American Cancer Society, CA: A Cancer Journal for Clinicians 2015 |
| CT of chest, abdomen and pelvis every 12 months for stages I to III, up to 5 years “Recommendation 5: Chest/abdominal/pelvic CT should be performed every 12 months (stages I-III) or every 3–6 months (stage IV, NED) for up to 5 years.” | 2A | American Cancer Society, CA: A Cancer Journal for Clinicians 2015 |
| Clearance colonoscopy within a year of diagnosis after curative resection | GRADE of evidence low; strength strong | BSG, ACPGBI and PHE, Gut 2020 |
| Next colonoscopy 3 years after the clearance colonoscopy | GRADE of evidence low; strength strong | BSG, ACPGBI and PHE, Gut 2020 |
| Intensive follow-up and overall survival “Overall survival: we found intensive follow-up made little or no difference (hazard ratio (HR) 0.91, 95% confidence interval (CI) 0.80 to 1.04: I² = 18%; high-quality evidence).” | high-quality evidence (GRADE): little or no difference | Cochrane Database of Systematic Reviews 2019 |
| Intensive follow-up and salvage surgery with curative intent “Salvage surgery with curative intent: this was more frequent with intensive follow-up (risk ratio (RR) 1.98, 95% CI 1.53 to 2.56; I² = 31%; high-quality evidence).” | high-quality evidence (GRADE): more frequent | Cochrane Database of Systematic Reviews 2019 |
Shares Risk-stratified follow-up: low-risk survivors to primary care with fast re-entry, National Institute for Health and Care Excellence, American Society of Clinical Oncology (ASCO), Survivorship care and late-effects surveillance and the tags protocol, follow-up, survivorship.
Shares National Institute for Health and Care Excellence, American Society of Clinical Oncology (ASCO) and the tags protocol, survivorship.
Shares American Society of Clinical Oncology (ASCO) and the tags protocol, survivorship.
Shares American Society of Clinical Oncology (ASCO) and the tags protocol, survivorship.
Shares National Institute for Health and Care Excellence, American Society of Clinical Oncology (ASCO) and the tags protocol, survivorship.
Shares Risk-stratified follow-up: low-risk survivors to primary care with fast re-entry, Survivorship care and late-effects surveillance and the tags follow-up, survivorship.
Shares National Institute for Health and Care Excellence, American Society of Clinical Oncology (ASCO) and the tag protocol.
Shares American Society of Clinical Oncology (ASCO) and the tags protocol, survivorship.