Slovenia 1988.

Methods	1988 to 1992 RCT
Participants	74 patients Stage III Trial data used in subgroup analyses for sex, age, histology, stage and nodal status
Interventions	Surgery + radiotherapy vs surgery alone RT details 30 Gy in 10 to 12 fractions in 2 weeks Prescription technique: central axis, at the midplane Machine used: linac Average field size (cm): 9 × 12 Clinical target volume: hilum, mediastinum Technique: oblique fields, lateral fields
Outcomes	Survival
Notes	Sealed envelope randomisation
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 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

All trials supplied individual participant data for analysis and therefore are defined as unpublished data, even though most are published.

IPD = individual participant data.
 RCT = randomised controlled trial.
 RT = radiotherapy.1G