Jubert 1978.

Study characteristics
Patient sampling	Country USA Study design Retrospective Setting Hospital Dates of data collection N/R Population (n) 97 Inclusion criteria Colorectal cancer Exclusion criteria N/R Participants Included (n) 97
Patient characteristics and setting	Age range 65 mean (39 ‐ 89) Smoking status Unknown Site of primary tumour Colon 56, rectum 41 Stage of primary tumour Dukes A 10, B 42, C 34, D 6 Perioperative investigations done to ensure no residual disease N/R Chemotherapy/radiotherapy? 5 chemo, 5 immuno Recurrences (n) 20 Site of recurrences 7 liver, 13 non‐liver
Index tests	CEA timing At 6‐week intervals postoperatively CEA technique N/R CEA threshold 2.5 µg/L Definition of positive 1 elevated value Which CEA value (s) used? At time of recurrence
Target condition and reference standard(s)	Follow‐up schedule CEA is done preoperatively and at six week intervals postoperatively. In addition, patients are evaluated postoperatively at 6 to 8 week intervals by physical examination and the usual laboratory and radiological tests, and where indicated, suspicions of recurrence and/or metastasis are documented histologically for the most part. Reference standard "suspicions of recurrence and/or metastasis are documented histologically for the most part".
Flow and timing	Timing of CEA vs reference standard (days) per protocol
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?	Unclear
		Unclear	Low
DOMAIN 2: Index Test All CEA thresholds
If a threshold was used, was it pre‐specified?	Unclear
Is the same method and instrument used for all CEA measurements?	Unclear
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
		Unclear	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	No
		Unclear	Unclear
DOMAIN 4: Flow and Timing
Did all patients receive the same reference standard?	Unclear
Were all patients included in the analysis?	Yes
Was the index test repeated prior to the reference standard?	No
Was the the timing between index test(s) and reference standard ascertainable?	Yes
Did all patients receive a reference standard?	Unclear
		Unclear