Introduction: Somatostatin analogues (SSA) prolong progression-free survival (PFS) in patients with well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs). However, the eligibility criteria in randomized clinical trials (RCTs) have been restricted, which contrasts with the vast heterogeneity found in NETs.
Methods: We identified patients with well-differentiated (Ki67% ≤20%), metastatic GEP-NETs treated in first-line with SSA monotherapy from the Spanish R-GETNE registry. The therapeutic effect was evaluated using a Bayesian Cox model. The objective was to compare survival-based outcomes from real world clinical practice versus RCTs.
Results: The dataset contained 535 patients with a median age of 62 years (range: 26-89). The median Ki67% was 4 (range: 0-20). The most common primary tumor sites were: midgut, 46%; pancreas, 34%; unknown primary, 10%; and colorectal, 10%. Half of the patients received octreotide LAR (n=266) and half, lanreotide autogel (n=269). The median PFS was 28.0 months (95% CI, 22.1-32.0) for octreotide vs 30.1 months (95% CI, 23.1-38.0) for lanreotide. The overall hazard ratio for lanreotide vs octreotide was 0.90 (95% credible interval, 0.71-1.12). The probability of effect sizes >30% with lanreotide vs octreotide was 2% and 6% for midgut and foregut NENs, respectively.
Conclusion: Our study evaluated the external validity of RCTs examining SSAs in the real world, as well as the main effect-modifying factors (progression status, symptoms, tumor site, specific metastases, and analytical data).. Our results indicate that both octreotide LAR and lanreotide autogel had a similar effect on PFS. Consequently, both represent valid alternatives in patients with well-differentiated, metastatic GEP-NENs.
Additive Functional Cox Model
