Hara 2010.

Study characteristics
Patient sampling	Country Japan Study design Retrospective Setting Hospital Dates of data collection 1990 ‐ 2004 Population (n) 488 Inclusion criteria Stage II or III curative resection Exclusion criteria Patients with squamous cell, carcinoma, more than one cancer, or insufficient follow‐up Participants Included (n) Stage II: 167 Stage III: 136
Patient characteristics and setting	Age range Stage II: 68.3 ± 10.5 (38 – 92) Stage III: 63.4 ± 9.4 (44 – 88) Smoking status N/R Site of primary tumour Stage II: Colon 112, rectum 55 Stage III: Colon 89, rectum 47 Stage of primary tumour Stage II: Depth T1 0, 2 0, 3 142, 4 23 Stage III: Depth T1 3, 2 89, 3 32, 4 12 Perioperative investigations done to ensure no residual disease Not specified Chemotherapy/radiotherapy? No Recurrences (n) Stage II: 23 Stage III: 51 Site of recurrences N/R
Index tests	CEA timing Unclear CEA technique N/R CEA threshold 5 µg/L Definition of positive N/R Which CEA value (s) used? N/R
Target condition and reference standard(s)	Follow‐up schedule All patients underwent routine serum CEA assays and radiological examination
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?	Yes
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?	Yes
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?	Unclear
		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?	Unclear
Was the the timing between index test(s) and reference standard ascertainable?	No
Did all patients receive a reference standard?	Unclear
		Unclear