Kjeldsen 1997

Methods	RCT (random numbers) Accrual: 1983 to 1994 Stratified for Dukes' stage and location Country: Denmark Setting: not stated Follow‐up: not stated
Participants	597 participants, (326 men and 271 women) treated with primary radical surgery for CRC, no residual neoplasia Inclusion criteria Aged less than 76 years No complicating disease making follow‐up impossible No other major cancer within the past 5 years Permanent residency within the county of Funen Dukes' A 138 Dukes' B: 293 Dukes' C: 166 Colon primary: 314 Rectal primary: 283
Interventions	The experimental group had follow‐up examinations at 6, 12, 18, 30, 36, 48, 60, 120, 150, and 180 months after radical surgery. The control group had examinations at 60, 120, and 180 months. Examinations included medical history, clinical examination, digital rectal examination (DRE), gynaecological examination, Haemoccult‐II test, colonoscopy, CXR, haemoglobin level, erythrocyte sedimentation rate, and liver enzymes.
Outcomes	Local recurrence Metachronous colorectal cancer Overall survival Cancer‐related survival
Notes	Definition of radical surgery: no residual neoplasia detected by the following examinations: complete colonoscopy or incomplete colonoscopy plus double‐contrast barium enema, CXR (2 views), histological evaluation of all surgical margins, biopsy of suspicious lesions (lymph nodes), inspection and palpation of liver during surgery Local recurrence was defined as growth in the region of the primary radical operation, including the surgical wound, and demonstrated clinically or by imaging techniques, but not necessarily verified by biopsy. New lesions were called metachronous when diagnosed at least 12 months after primary cancer
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote (page 666): "After surgery, the patients were allocated to one of two follow‐up programmes (groups 1 and 2) by random numbers." Comment: the use of random numbers may be adequate, but there is not enough description to be certain; therefore, we graded this as unclear.
Allocation concealment (selection bias)	Unclear risk	Quote (page 666): "After surgery, the patients were allocated to one of two follow‐up programmes (groups 1 and 2) by random numbers." Comment: there was no description of concealment of allocation, so it was probably not done.
Blinding of participants and personnel	Unclear risk	Quote (page 666): "All patients were also instructed to visit their general practitioner if they developed abdominal pain or changing bowel habits lasting more than 2 weeks after the immediate postoperative period." Comment: Participants: not mentioned, although it is possible that those participants in the minimal follow‐up group may have put more weight on their symptoms in the knowledge that they had fewer planned investigations. We judged that this domain was probably not at risk of bias. Assessors: not mentioned, but there is a risk that in the minimal follow‐up group, personnel may have put more weight on reported symptoms in the knowledge that they had fewer planned investigations. However, there were prespecified follow‐up schedules.
Blinding of outcome assessment	High risk	Quote (page 666): "Local recurrence was defined as growth in the region of the primary radical operation, including the surgical wound, and demonstrated clinically or by imaging techniques, but not necessarily verified by biopsy." Quote (page 666): "Group 1 had follow‐up examinations at 6, 12, 18, 24, 30, 36, 48, 60, 120, 150 and 180 months after radical surgery, while group 2 had examinations at 60, 120 and 180 months." Objective outcomes: blinding not mentioned (likely to be a source of bias) Subjective outcomes: not measured
Incomplete outcome data (attrition and exclusions)	Low risk	Quote (page 668): "In all, 88 of 290 patients in group 1 and 100 of 307 in group 2 have died." Comment: this implies that they had followed all participants.
Selective reporting (reporting bias)	Unclear risk	Quote (page 666): "The main purpose of the present randomised study was to evaluate the possible influence of follow‐up upon survival." "Recurrence (and/or distant spread)" Comment: the primary outcome of survival was reported on in the results. There were multiple outcomes reported, but as we were not able to review the protocol, we judged the risk of bias for this domain as "unclear". Outcomes reported included the following: recurrence (local, distant, symptomatic, and asymptomatic) "cancer‐free time" curative salvage surgery metachronous primaries colorectal cancer deaths
Other sources of bias	Unclear risk	We detected no other bias.