Carpelan‐Holmström 2004.

Study characteristics
Patient sampling	Country Finland Study Design Retrospective Setting Hospital Dates of data collection N/R Population (n) 354 Inclusion criteria Curative surgery, but unclear Exclusion criteria Palliative, followed up elsewhere, no preoperative serum samples, no serum at the time of recurrence Participants included (n) 102
Patient characteristics and setting	Age range 29 ‐ 88 yrs Smoking status N/R Site of primary tumour Colorectal Stage of primary tumour Dukes A ‐ D (16 Dukes A, 45 Dukes B, 34 Dukes C, and 7 Dukes D) Perioperative investigations done to ensure no residual disease N/R Chemotherapy/radiotherapy? N/R Recurrences (n) 40 Site of recurrences Local 17, Liver 10, Various 13
Index tests	CEA timing N/R CEA technique CEA was measured with a time‐resolved immunofluorometric assay (AutoDELFIA®; Wallac, Turku, Finland). The detection limit of the assay is 0.2 µg/L, and the inter‐assay coefficient of variation is 3% in the concentration range 3 – 90 µg/L (total CV 4%) CEA threshold 5 µg/L Definition of positive 1 elevated value Which CEA value (s) used? At time of recurrence
Target condition and reference standard(s)	Reference standard Clinical follow‐up
Flow and timing	Timing of CEA vs reference standard (days) Unclear
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	Unclear
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?	Yes
Is there an indication of method accuracy, for example, is there evidence of participation in an external quality assessment and proficiency testing scheme?	Yes
		Low	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