Minimally important differences for interpreting European Organisation for Research and Treatment of Cancer (EORTC) Quality of life Questionnaire core 30 scores in patients with ovarian cancer

•Our study has determine MIDs for interpreting group-level change of EORTC QLQ-C30 scores in patients with ovarian cancer•MIDs varied by scale, direction of change and ranged from 4 to 10 points for most EORTC QLQ-C30 scales•Our findings show that a global rule for MIDs applicable to all settings is highly unlikely•Our findings also reinforce evidence that scale specific MIDs should be selected with caution.•The presented MIDs will facilitate interpretation of group-level change of EORTC QLQ-C30 scores in ovarian cancer trials