GILDA 1998

Methods	RCT Accrual dates: 1998 to 2006 Multicentered, international study Median follow‐up: 62 months Setting: not stated
Participants	1228 participants (746 men and 482 women) with histopathologic diagnosis of adenocarcinoma of the colon or rectum, Dukes Astler‐Coller stage B2‐C, treated with curative intent (radical excision plus or minus adjuvant radio/chemotherapy) Participant must be free of known cancer prior to entry, attested by normal endoscopy, US, CXR, and CEA Exclusion criteria Inability to undergo testing (disability, allergy to contrast, etc.) or geographically not amenable to follow‐up Enrolment in any other protocol requiring specific follow‐up practice History of any previous malignancy in the last 10 years (other than CIS of the cervix or non‐melanoma skin cancer) No informed consent
Interventions	Experimental group programme 4, 8, 12, 16, 20, 24, 30, 36, 42, 48, and 60 monthly office visits and history and clinical examination, FBC, CEA, and CA 19‐9 Colonoscopy and CXR at 12, 24, 36, 48, and 60 months Liver US at 4, 8, 12, 16, 24, 36, 48, and 60 months For rectal participants, pelvic CT at 4, 12, 24, and 48 months Control group programme 4, 8, 12, 16, 20, 24, 30, 42, 48, and 60 monthly office visits, including history, examination, and CEA Colonoscopy at 12 and 48 months Liver ultrasound at 4 and 16 months Rectal cancer participants in addition had rectoscopy at 4 months, CXR at 12 months, and liver US at 8 and 16 months. A single pelvic CT was allowed if a radiation oncologist required it as baseline following adjuvant treatment
Outcomes	Principal endpoints Overall survival Specific mortality Secondary endpoints Quantify lead time due to intensive programme Treatment of recurrences with curative intent Sensitivity of follow‐up regimens Compliance with follow‐up regimen Quality of life HRQoL self‐assessed at baseline and at 12, 24, 36, 48, and 60 months Relapsed participants were monitored every two months for 1 year using EORTC QLQ‐C30
Notes	‐
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote (abstract, page 274): "Colon cancer patients were randomised." Comment: as no details were given, we deemed this domain to be at unclear risk of bias.
Allocation concealment (selection bias)	Unclear risk	Quote (paragraph 5, page 6): "Randomisation was performed centrally via telephone at the...Italy." Comment: this implied that randomisation was remote and potentially concealed, but the details were not given.
Blinding of participants and personnel	Unclear risk	There was no mention of blinding of either participants or personnel, so this was probably not done.
Blinding of outcome assessment	Unclear risk	There was no mention of blinding with regard to the outcome assessors, so this was probably not done.
Incomplete outcome data (attrition and exclusions)	Low risk	Quote (figure 2, Rosati 2016): "3 patients from 3 centres that ceased collaboration soon after randomisation, four patients not eligible..." Comment: the study gave details of reasons for exclusions and attrition by arm, so we judged this domain as not at high risk of bias.
Selective reporting (reporting bias)	Unclear risk	The study reports on the primary outcome and selected secondary outcomes (quality of life measures). We did not have access to the study protocol, so we judged this domain to be at unclear risk of bias.
Other sources of bias	Unclear risk	We detected no other bias.