Olweny 1977.

Methods	Randomised, parallel group, single‐centre trial (Kenya). ITT: no. Withdrawals: stated.
Participants	Baseline characteristics: 25 participants randomised; 22 participated. Median age: irradiation: 8 years; no irradiation: 5 years (range: 4 to 14). Tumour staging: Ziegler and Magrath. Diagnosis: histology or cytology. Entry criteria: BL free of CNS involvement in remission post treatment with C, MTX, or O.
Interventions	Irradiation versus no irradiation. Dose given was 20 to 24 Gy (0.7 to 0.75 Gy per fraction). Treatment duration: 2 x 5 days. Follow‐up: 1.6 years.
Outcomes	Relapse. Overall survival.
Notes	Full text publication. a follow‐up on Olweny 1976. Study type: remittance maintenance.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Stated as "previously prepared random cards".
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding (performance bias and detection bias) All outcomes	High risk	The authors made adjustments for the number that were unable to make the trip to the treatment venue.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcomes were described for all participants.