Retrospective analysis of the efficacy of somatostatin analogs (SSA) in metastatic pulmonary neuroendocrine tumors and prognostic significance of FDG-PET

Background

Pulmonary carcinoids (PCs) are classified according to 2004 WHO criteria as typical (TC) or atypical (AC). Data on palliative treatment are extrapolated from studies of mixed populations. Over the past few years SSAs have been assessed in gastroenteopancreatic neuroendocrine tumors but trials are lacking on PCs. The aim of this study was to retrospectively evaluate the efficacy of SSAs in metastatic PCs and to define prognostic factors.

Methods

From January 2007 to February 2015, 30 patients with metastatic PCs received SSAs as first-line treatment (20 patients with octreotide LAR 30 mg and 10 with lanreotide 120 mg every 28 days). Eight (23.3%) patients had TC and 23 (76.7%) AC. Progression-free survival (PFS) was estimated by the Kaplan-Meier method and 95% confidence intervals (95%CI) were reported. Differences between groups were assessed using the log-rank test.

Results

All patients (23 male and 7 female) were Ga68PET/CT- or octreoscan-positive. Of the 20 patients who performed PET/FDG, 14 (70.0%) were positive and 6 negative (30.0%). Median age was 65.5 years (range 47-82) and ECOG performance status (PS) at diagnosis was 0 for 14 (46.7%) patients, 1 (36.7%) for 11 and 2 (16.6%) for 5. Eight (23.3%) patients had TC and 23 (76.7%) AC. The median treatment duration was 10 months (range 2-59). Of the 27 evaluable patients, one (3.3%) achieved a partial response and 26 (86.6%) showed stable disease. As second-line treatment, 6 (20%) patients underwent chemotherapy and 23 (76.7%) radionuclide therapy. One patient stopped SSAs due to symptomatic cholelithiasis. The 5-year survival rate was 53% (95%CI 15-80). Median PFS (mPFS) was 11 months (95%CI: 7-15). Patients with negative PET/FDG had a mPFS of 15 months (95%CI:7-not reached), while those with positive PET/FDG showed a 7-month mPFS (95%CI: 4-10). This difference was significant (p-value = 0.0154). No differences in mPFS were observed on the basis of TTF1 value, histological subtype or presence of extrahepatic metastases.

Conclusions

SSAs showed antitumor activity in terms of disease control rate and PFS. It also proved safe, even in patients with poor PS. FDG/PET would appear to be a prognostic factor in patients with metastatic PCs.

Clinical trial identification

ID653-L1P33

Legal entity responsible for the study

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori I.R.S.T

Funding

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori I.R.S.T

Disclosure

All authors have declared no conflicts of interest.