01Core principlesThe concepts and mechanisms needed to understand the subject.
After potentially curative surgery for non-metastatic colorectal cancer, surveillance aims to detect local, liver or lung recurrence while still amenable to treatment and to clear the remaining colon. NICE specifies first-three-year follow-up with CEA and CT chest, abdomen and pelvis; its quality standard describes CEA at least every six months, at least two CT examinations and clearance colonoscopy within one year of diagnosis. BSG recommends the next colonoscopy three years after that one-year clearance examination, with later surveillance based on findings, fitness and whether treatment would offer benefit.
Scheduled cancer tests cannot replace assessment of new symptoms, and CEA is an adjunct rather than a rule-out marker. Survivorship also includes bowel, urinary, sexual, nutritional, psychological and stoma outcomes. Low anterior resection syndrome causes frequency, urgency, fragmentation, incomplete emptying and difficulty distinguishing flatus from stool; NICE recommends a validated LARS questionnaire and symptom-directed treatment, with secondary-care advice when initial measures fail.
Key points
- Surveillance intensity depends on tumour site, stage, treatment, resection status, fitness for salvage and national or local protocol.
- CEA can support recurrence detection after colorectal resection but smoking, inflammation and non-secreting tumours limit interpretation.
- CT surveillance looks for resectable liver, lung, nodal or local recurrence; symptoms still require assessment between planned scans.
- Colonoscopy detects metachronous neoplasia and checks the remaining colon after any incomplete preoperative assessment.
- Rectal surgery can cause low anterior resection syndrome, urinary and sexual dysfunction; pelvic radiotherapy adds bowel, bladder and bone effects.
- Anal chemoradiotherapy may cause chronic skin change, stenosis, incontinence, sexual dysfunction and lymphoedema.
02Mechanisms and patternsImportant relationships and how to distinguish them.
New weight loss, abdominal or pelvic pain, bleeding, cough, breathlessness, jaundice, distension or altered bowel habit needs assessment when it occurs even after a normal scan or CEA.
Some tumours do not secrete CEA and smoking, inflammation or other disease can raise it; use a confirmed trend with clinical assessment and cross-sectional imaging.
Frequency, urgency, clustering, incontinence, incomplete emptying and difficulty separating wind from stool reflect reduced reservoir, altered motility and sphincter effects after rectal resection.
Chronic proctopathy, bowel urgency, urinary symptoms, sexual dysfunction, vaginal stenosis, pelvic insufficiency fracture and lymphoedema may appear months or years after treatment.
Leakage, skin injury, retraction, prolapse, parastomal hernia, high output and altered body image need direct examination and access to stoma and surgical support.
03Interpreting evidenceInformation, measurements and their limitations.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Serial serum CEA - Why
- Support detection of colorectal recurrence after potentially curative treatment.
- Interpretation and limitations
- Measure at least every six months in the first three years under the NICE quality standard; confirm and image an unexplained rise, but do not use a normal result to dismiss symptoms.
- 02
CT chest, abdomen and pelvis - Why
- Detect local, nodal, liver, lung and peritoneal recurrence.
- Interpretation and limitations
- NICE quality standards specify at least two CT scans in the first three years; comparison with baseline and specialist review determine whether a lesion is salvageable.
- 03
Clearance and surveillance colonoscopy - Why
- Complete any unexamined colon and detect metachronous cancer or high-risk polyps.
- Interpretation and limitations
- Clearance colonoscopy should occur within one year of diagnosis, with later interval determined by findings, examination quality and BSG post-resection guidance.
- 04
LARS score and functional assessment - Why
- Quantify bowel dysfunction after sphincter-preserving rectal surgery and its quality-of-life effect.
- Interpretation and limitations
- A validated patient questionnaire identifies no, minor or major LARS but does not exclude recurrence; red flags still need structural assessment.
- 05
Targeted late-effect investigations - Why
- Distinguish treatment toxicity from recurrence, infection, malabsorption or mechanical disease.
- Interpretation and limitations
- Use endoscopy, stool tests, renal or nutritional tests, pelvic imaging and specialist examination according to the actual symptom rather than a generic survivorship panel.
04Applied reasoningWorked examples connecting principles to decisions.
01Worked case: rising CEA with a treatable liver recurrenceTurn surveillance abnormality into a verified salvage decisionEighteen months after R0 stage III colon-cancer resection and adjuvant treatment, an asymptomatic 63-year-old has CEA rising from 3 to 11 then 18 micrograms/L on repeat testing.+
- 1Review the original tumour’s CEA secretion, pathology and surveillance record and assess weight, abdomen, respiratory symptoms and performance status rather than treating the marker in isolation.
- 2Repeat CEA to confirm the trend and obtain contrast CT chest, abdomen and pelvis, which identifies a new solitary segment VI liver lesion without other recurrence.
- 3Dedicated liver MRI confirms one technically resectable metastasis; refer promptly to the hepatobiliary MDT instead of waiting for the next routine CT.
- 4The patient undergoes parenchymal-sparing liver resection and pathology confirms a colorectal metastasis removed with a clear margin.
- 5Verify the actual histology, postoperative oncology decision and revised cross-sectional, CEA and colonoscopy schedule and continue functional and late-effect review.
02New symptoms despite a normal markerInvestigate the clinical change rather than waiting for CEATwo years after low anterior resection, a 66-year-old develops 5 kg weight loss, pelvic ache and newly worsening bowel frequency. CEA remains 2 micrograms/L.+
- 1Take a detailed bowel and systemic history, assess the stoma if present and examine the abdomen, perineum and rectum when anatomically appropriate.
- 2Explain that normal CEA cannot exclude marker-negative recurrence and bring forward CT chest, abdomen and pelvis plus local pelvic imaging and endoscopic assessment.
- 3MRI identifies a presacral mass and biopsy confirms local adenocarcinoma recurrence; discuss resectability at a specialist recurrent rectal-cancer MDT.
- 4Verify the named treatment decision and symptom support and communicate that new obstruction, bleeding or rapid pain escalation warrants emergency review.
03Major low anterior resection syndromeMeasure, exclude structural disease and treat the dominant dysfunctionNine months after sphincter-preserving rectal surgery, a patient has 12 clustered bowel actions daily, urgency, accidents and difficulty distinguishing flatus from stool but no weight loss, bleeding or pain.+
- 1Use the validated patient-administered LARS score, which is 36 and therefore records major symptom burden, and assess dietary triggers, medicines, anastomotic symptoms and quality-of-life impact.
- 2Check examination and completed cancer surveillance for recurrence or anastomotic narrowing before labelling every symptom functional; no structural problem is found.
- 3Because the dominant pattern is frequent watery clustered stool, start loperamide 2 mg orally 30 minutes before breakfast and 2 mg before the evening meal, then review after one week and adjust in 2 mg daily increments toward one to two formed stools; do not exceed 16 mg daily. Pair this with individual dietary and bowel-routine advice rather than giving ispaghula automatically for watery output.
- 4At six-week review on loperamide 2 mg before breakfast, lunch and the evening meal, frequency has fallen to six daily and accidents to one weekly without constipation or distension, but major impairment persists, so seek specialist colorectal, dietetic and pelvic-floor input.
- 5Verify the repeat LARS score, treatment tolerance and escalation options rather than accepting severe dysfunction as an inevitable consequence of cure.
05Relevant medicines and safetySpecific regimens and precautions where medicines are relevant.
Loperamide for watery high-frequency LARS
After excluding recurrence, anastomotic narrowing, infection and active inflammation, start 2 mg orally 30 minutes before breakfast and 2 mg before the evening meal; review within one week and titrate by 2 mg daily toward one to two formed stools, not exceeding 16 mg daily.Do not use with ileus, abdominal distension, acute dysentery, severe active colitis or suspected bacterial enterocolitis; stop for constipation or increasing distension, use caution in hepatic impairment and avoid doses above the licensed maximum because serious cardiac toxicity occurs with overdose.
06Checking understandingVerify the reasoning, revisit uncertainties and apply feedback.
- For potentially curatively treated non-metastatic colorectal cancer, track CEA and CT completion through the first three years and record each result and owner.
- Confirm clearance colonoscopy within one year of diagnosis and the subsequent BSG colonoscopy three years later; record preparation, completion, polyp histology, fitness for intervention and any findings-based change to later intervals.
- At every contact ask about bowel, stoma, urinary and sexual function, nutrition, mood and ability to work or travel rather than limiting review to recurrence tests.
- Investigate new alarm symptoms immediately and interpret an unexplained CEA rise with repeat measurement and imaging; neither marker nor calendar date should delay assessment.
- When LARS treatment starts, repeat a validated score and record the symptom most important to the patient, adverse effects and whether secondary-care advice is needed.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Surveillance needs salvage intent
Tests add most value when detecting recurrence would lead to potentially beneficial treatment.
Function is an outcome
Bowel control, stoma problems, urinary and sexual health deserve active assessment rather than being treated as inevitable.
Markers have blind spots
Some tumours do not secrete CEA and non-malignant conditions can raise it.
Transitions lose patients
A written plan shared among oncology, surgery, primary care and the patient prevents missed tests and duplicated uncertainty.
08Common pitfallsFrequent interpretation and management errors.
- 01
Reassuring a symptomatic patient from one normal CEA can miss marker-negative recurrence.
- 02
Waiting for the next routine CT despite new obstruction symptoms confuses scheduled surveillance with clinical assessment.
- 03
Recording cancer free without asking about continence, stoma, urinary or sexual effects overlooks treatable morbidity.
- 04
Ordering repeated tests without confirming that the patient is fit for and wants salvage treatment may create burden without benefit.