Background Gastroenteropancreatic neuroendocrine tumours (GEP-NET) are a rare, life-threatening type of cancer. The survival benefit of Lu-177-DOTATATE has been demonstrated in GEP-NET patients. Health technology assessment bodies require data on health-related utility impacts of treatment. A cancer-specific instrument, EORTC QLQ-C30, was used to collect the data for Lu-177-DOTATATE within clinical studies, but utility-based instruments were not included. Objective The main aim of this study was to compare EQ-5D-3L and QLU-C10D utilities obtained from EORTC QLQ-C30 using two different approaches. A secondary aim was to analyse the EQ-5D-3L and QLU-C10D utilities of patients treated with Lu-177-DOTATATE versus best supportive care. A supplementary aim was to evaluate the effect of Lu-177-DOTATATE on patients' health-related utility over time. Methods Three datasets were used for the analysis. NETTER-1 is a clinical trial, whilst ERASMUS and Guy's and St. Thomas (GStT) are real-world datasets. Two mapping algorithms (response mapping and ordinary least square regression) were applied to generate EQ-5D-3L utilities from EORTC QLQ-C30. An algorithm was used to obtain QLU-C10D utilities from EORTC QLQ-C30. Results In all studies, EQ-5D-3L utilities were higher than QLU-C10D utilities at most time points measured, although the magnitude of the differences was small. In NETTER-1, EQ-5D-3L and QLU-C10D utilities were higher in the Lu-177-DOTATATE arm compared with the octreotide long-acting release (LAR) arm, overall and pre-progression. In all studies, patients' health-related utilities seem to be maintained over time. Conclusion There were small differences between EQ-5D-3L and QLU-C10D utilities, but these did not translate to relative differences over time or between groups. In NETTER-1, patients in the Lu-177-DOTATATE arm had higher health-related utilities than patients in the octreotide LAR arm. Health-related utility may at least remain maintained in patients with GEP-NET receiving Lu-177-DOTATATE.
