Abstract Importance Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) can affect patient health-related quality of life (HRQoL). Appropriate information may improve their adherence to treatment and quality of life. Objective To evaluate the change in patient's perceptions of the level of information at lanreotide (LAN) treatment initiation for GEP-NETs vs after 6 months. Design OPERA (NCT03562091) was a prospective, longitudinal, noninterventional study. Setting Thirty-one centers in France specialized in the management of patients with NETs. Intervention Planned clinical visits at enrollment and end-of-study visits at month 6, with completion of the European Organisation for Research and Treatment of Cancer 25-item Quality of Life Questionnaire—Information Module (QLQ-INFO25) and 30-item Quality of Life Questionnaire—Core. Main outcome Absolute change in the patient's perception of the information between baseline and month 6, using the relevant domains of the QLQ-INFO25. Endpoints measured at baseline and month 6 for at least 1 of the 3 targeted QLQ-INFO25 dimensions of the primary endpoint. Results Ninety-three of the 115 patients enrolled completed ≥1 primary endpoint information dimension. Mean (SD) scores for the primary endpoint information dimensions were high at baseline (disease, 63.41 [20.71]; treatment, 58.85 [19.00]; supportive care, 26.53 [24.69]; maximum 100). There were no significant changes between baseline (98.34% CI) and 6 months (disease, −2.84 [−8.69, 3.01; P = .24]; treatment, −4.37 [−11.26, 2.52; P = .13]; supportive care, 0.46 [−6.78, 7.70; P = .88]), and in HRQoL between baseline and 6 months. Conclusions and relevance The lack of change in patient's perceptions of the disease, treatment, and supportive care information provided over the first 6 months of LAN treatment may suggest that physicians provided adequate information at the treatment initiation.