Minimal important differences of EORTC QLQ-C30 and QLQ-BR23 for metastatic breast cancer patients in a Japanese population: results from the RESQ trial.

BACKGROUND

European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and breast cancer–specific quality-of-life questionnaire (QLQ-BR23) are widely used in clinical trials, but information on minimal important differences (MIDs) remain limited.

METHODS

Data were obtained from the RESQ trial, a phase 3 study conducted in Japan. A total of 302 patients with HER2-negative metastatic breast cancer were randomized to receive eribulin or S-1. QLQ-C30 and QLQ-BR23 were administered every six weeks until week 24 and every nine weeks until week 42. The trial’s preplanned secondary analysis aimed to estimate group-level MIDs for both questionnaires. Subjective significance questionnaire and performance status (PS) served as anchors to estimate MIDs.

RESULTS

Of the 302 patients, 270 were included in this analysis. The median age was 61 years. At baseline, 73.0% had a PS of 0, and 27.0% had a PS of 1 or 2. Within-group MIDs were estimated for 11 domains of the QLQ-C30 and 5 domains of the QLQ-BR23, ranging from 6 to 14 points for improvement and − 5 to − 17 points for deterioration. Between-group MIDs were estimated for 7 domains of the QLQ-C30, ranging from 4 to 7 points for improvement and − 4 to − 9 points for deterioration; none were estimated for the QLQ-BR23.

CONCLUSIONS

This study provides the first MID estimates for the QLQ-BR23 and expands MID for the QLQ-C30 in patients with metastatic breast cancer. These findings offer benchmarks for interpreting quality-of-life outcomes and support the clinical relevance of patient-reported measures.[ 250 / 250 ].