OBJECTIVES: This study examined real-world metastatic neuroendocrine tumor treatment patterns and outcomes in two cohorts matched by first-therapy somatostatin analogues (SSA).

METHODS: A retrospective cohort of metastatic gastroenteropancreatic and pulmonary neuroendocrine tumor patients who received first-line octreotide or lanreotide at IRST from 2009 to 2022 was retrieved from hospital electronic health records. The cohorts were matched 1:1 by first-line SSA treatment, sex, age, cancer site, and year of diagnosis. The Kaplan-Meier survival estimates and the Cox proportional hazard model were utilized to analyze progression-free survival (PFS) and overall survival (OS).

RESULTS: Of 441 eligible patients, 310 were matched (N=155 for octreotide and lanreotide groups, respectively). 63.5% of patients started SSA alone, whereas 36.5% started SSA in combination with other therapies. Among the 245 (79.0%) patients who received second-line treatment, 188 continued SSA in combination with other therapies. The most used second-line therapies were lanreotide (29.5%) and octreotide (28.7%), combined with radioligand therapy. No treatment trends were identified in subsequent lines. Lanreotide and octreotide had comparable median PFS of 15.5 (95%CI:13.6-19.1) and 14.0 (95%CI:12.0-15.8) months, respectively (p=0.07). However, from the Cox model, octreotide was associated with a 34% (HR 95%CI:1.06-1.71) higher risk of progression than lanreotide (p=0.02). The presence of multiple metastases (HR=1.45,95%CI:1.13-1.87) and a Ki67>20 (HR=2.34,95%CI:1.43-3.83) were shown to be significantly related to a lower PFS. The observed median OS was 10.4 (95%CI:7.5-NA) and 9.2 (95%CI:7.3-NA) years for patients undergoing first-line treatment with lanreotide and octreotide, respectively. Notably, patients with bone metastases had a 91% (HR 95%CI:1.14-3.20) higher mortality risk (p=0.01).

CONCLUSIONS: Most patients start with SSA monotherapy. In subsequent treatments, most patients receive SSA with additional therapies. First-line long-acting octreotide and lanreotide showed comparable PFS and OS. Interestingly, octreotide exhibited a 34% higher occurrence of disease progression.