Belgium 1966.

Methods	1966 to 1977 RCT
Participants	224 patients Stages I, II, III Trial data used in subgroup analyses for sex, age and histology
Interventions	Surgery + radiotherapy vs surgery alone RT details 60 Gy in 30 fractions in 6 weeks Prescription technique: isodose 90% Machine used: Co60 Average field size (cm): 15 × 9 Clinical target volume: bronchial stump, hilum, mediastinum Technique: spinal cord blocks, oblique fields, lateral fields
Outcomes	Survival
Notes	20 small cell participants excluded from meta‐analysis Unable to supply data for 2 participants
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Comment: stated as randomised in paper; checks run on IPD suggest adequate sequence generation
Allocation concealment (selection bias)	Low risk	Quote: "randomisation carried out via sealed envelope"
Blinding (performance bias and detection bias) All outcomes	Low risk	Comment: trial not blinded owing to the nature of the intervention; outcome not likely to be influenced by lack of blinding
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: individual participant data obtained and checked for all outcomes
Selective reporting (reporting bias)	Low risk	Comment: individual participant data obtained and checked for all outcomes
Other bias	Low risk	Comment: study apparently free of other sources of bias