Schoemaker 1998

Methods	RCT Accrual: 1984 to 1990 2 centres in the trial Stratified according to site (colon or rectum) and Dukes' stage Setting: tertiary centres Follow‐up: 60 months
Participants	325 participants (207 men and 118 women) who had curative resection of newly diagnosed CRC Exclusion criteria Medical comorbidity making follow‐up difficult or 5‐year survival unlikely Residence in a remote area Aged > 85 years Refusal to participate in the trial Evidence of residual or distant malignancy Dukes' A: 71 Dukes' B: 153 Dukes' C: 101 Colon primary: 238 Rectal primary: 87 Country: Australia
Interventions	Participants in the experimental arm underwent yearly CXR, CT of the liver, and colonoscopy. These investigations were only performed in the control group if indicated on clinical grounds or after screening test abnormality, and at 5 years of follow‐up, to exclude a reservoir of undetected recurrences.
Outcomes	Overall survival
Notes	Both groups had regular clinical review, including history, examination, and screening investigation at 3, 6, 9, 12, 15, 21, 24, 30, 36, 42, 48, 54, and 60 months or until a major endpoint was reached. A nurse research assistant performed a review at each visit, and a consultant surgeon, on at least alternate visits. Clinical signs and symptoms were recorded on a structured ProForma. Screening investigations at each visit comprised of FBC, LFTs, CEA, and faecal occult blood testing using the Haemoccult‐II test (without hydration) on 3 faecal samples. All screening or clinical abnormalities were investigated on merit. The only exception was CEA ‐ an isolated rise in CEA was not used to trigger further investigations.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote (page 8): "The patients were then randomized to either standard or intensive follow‐up by choosing the next card from a box of cards indicating the type of follow‐up. The cards had been previously randomized using random tables." Comment: this is an adequate method of sequence generation.
Allocation concealment (selection bias)	High risk	Quote (page 8): "The patients were then randomized to either standard or intensive follow‐up by choosing the next card from a box of cards indicating the type of follow‐up." Comment: the study did not report details about how this was done, so we conclude that it makes this domain at high risk of bias.
Blinding of participants and personnel	Low risk	Quote (page 8): "Review was performed by a nurse research assistant at each visit and by a consultant surgeon on at least alternate visits. Clinical symptoms and signs were obtained and recorded on a structured pro forma." Comment: the study did not mention blinding of participants and personnel, but it would have been difficult to do and unlikely to have introduced bias. The use of the pro‐forma for data collection on symptoms and signs would reduce the risk of bias from lack of personnel and participant blinding.
Blinding of outcome assessment	Low risk	Quote (page 8): "CXR and CT scans were interpreted by an independent senior radiologist. Colonoscopies were performed or supervised by recognized accredited colonoscopists and aimed to examine the entire residual colon to identify recurrence, metachronous carcinoma, and polyps." Comment: blinding of outcome assessors was likely to reduce the risk of bias.
Incomplete outcome data (attrition and exclusions)	Low risk	Quote (page 8): "Eighteen patients withdrew from the study (standard, 8; intensive, 10). Three patients from each group were lost to follow‐up at intervals ranging from 9 to 54 months because they moved to another state. Five patients in the standard group and 7 in the intensive group withdrew at intervals ranging from 3 to 54 months because of development of other medical illnesses that precluded further structured follow‐up." Comment: the study did not report postrandomisation exclusions. This attrition has been reported by study arm and the reasons are similar for the 2 arms, it is thus unlikely to be a source of bias.
Selective reporting (reporting bias)	Unclear risk	Outcomes specified in the methods Survival Outcomes actually reported in the paper Withdrawals Survival Recurrences Metachronous primaries Investigations Colonoscopies plus complications CT scans CXR Lung and liver recurrences and survival after resection of these We did not have access to the study protocol, so we judged the risk of bias for this domain to be unclear.
Other sources of bias	Unclear risk	We detected no other bias.