Berek 2009.

Methods	Randomised placebo‐controlled phase III trial
Participants	371 stage III/IV ovarian cancer patients with complete clinical response to primary therapy
Interventions	Intravenous monoclonal antibody (oregovomab) vs placebo
Outcomes	Survival (time to relapse) Immune responses Adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Centralised randomisation procedure
Allocation concealment (selection bias)	Low risk	Centralised randomisation procedure
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinded to treatment assignment, post‐randomisation immune responses, and CA‐125 measurements
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded to treatment assignment, post‐randomisation immune responses, and CA‐125 measurements
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups
Selective reporting (reporting bias)	Unclear risk	Information insufficient to permit judgement of ‘low risk’ or ‘high risk’
Other bias	Low risk	No other sources of bias detected