Triboulet 1983.

Study characteristics
Patient sampling	Country France Study design Prospective cohort study Setting Hospital Dates of data collection 1976 ‐ 1979 Population (n) 91 Inclusion criteria Operated on with curative intent for colorectal cancer Exclusion criteria Conditions which could affect B2 microglobulin level: altered renal function (creatinine > 88.4 umol/l); liver disease: chronic active cirrhosis, primary biliary cirrhosis, acute hepatitis. Metastasis or Dukes D cancers. Patients whose CEA had not returned to normal within 3 months of the operation.
Patient characteristics and setting	Participants included (n) 91 Age range 33 ‐ 80 Smoking status N/R Site of primary tumour Colon 65, rectum 26 Stage of primary tumour Dukes A&B = 50; C = 41 Perioperative investigations done to ensure no residual disease N/R Chemotherapy/radiotherapy? No Recurrences (n) 43 Site of recurrences 12 rectum, 31 colon
Index tests	CEA timing Every 3 months CEA technique Radioimmunoassay (sorin) CEA threshold 20 µg/L Definition of positive N/R Which CEA value (s) used? N/R
Target condition and reference standard(s)	Follow‐up schedule CEA & B2m every 3 months for at least 2 years. Clinical and laboratory monitoring was ensured by the same physician during the first two years post‐op in a pre‐established protocol with a barium enema and / or an endoscopy during the first two years enema. CXR and Liver USS annually. Further investigations if indicated (CT chest, bone scan)
Flow and timing	Timing of CEA vs reference standard (days) Yearly CXR and liver USS; enema and/or endoscopy done at least once in the 2 year follow‐up
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Did the study avoid inappropriate exclusions?	No
		High	Low
DOMAIN 2: Index Test All CEA thresholds
If a threshold was used, was it pre‐specified?	Yes
Is the same method and instrument used for all CEA measurements?	Yes
Is there an estimation of reproducibility of the method, for example the % coefficient of variation at specific concentrations?	No
Is there an indication of method accuracy, for example, is there evidence of participation in an external quality assessment and proficiency testing scheme?	No
		Low	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	No
		Low	Low
DOMAIN 4: Flow and Timing
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Was the index test repeated prior to the reference standard?	Unclear
Was the the timing between index test(s) and reference standard ascertainable?	Unclear
Did all patients receive a reference standard?	No
		High