Outcome Analysis of First-line Somatostatin Analog Treatment in Metastatic Pulmonary Neuroendocrine Tumors and Prognostic Significance of ¹⁸FDG-PET/CT

Introduction: Pulmonary carcinoids (PCs) are classed according to the World Health Organization 2004 classification as typical or atypical carcinoids. Owing to their rarity, no dedicated clinical trials with somatostatin analogs (SSAs) have been carried out on primary PCs. Patients and Methods: From January 2007 to December 2015, 30 patients with metastatic PCs underwent first-line SSA treatment (20 with octreotide long-acting repeatable 30 mg and 10 with lanreotide 120 mg every 28 days). Eight (23.3%) patients had typical carcinoids and 23 (76.7%) had atypical carcinoids. Results: The median age was 65.5 years (range, 47-82 years). All patients (23 males and 7 females) were Gallium-68-DOTA-TOC-positron emission tomography/computed tomography (PET/CT)-positive (29 patients) or octreoscan-positive (1 patient). Of the 20 patients who performed fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG-PET/CT), 14 (70.0%) were positive and 6 negative (30.0%). The median treatment duration was 10 months (range, 2-59 months). One patient achieved a partial response (3.3%), and 26 (86.6%) showed stable disease. One patient interrupted SSA treatment owing to symptomatic cholelithiasis. Five-year survival was 53.0% (95% confidence interval [CI], 15.0%-80.0%). The median progression-free survival (mPFS) was 11.1 months (95% CI, 7.0-15.0 months). Negative ¹⁸FDG-PET/CT patients had an mPFS of 15.2 months (95% CI, 7.6 months to not reached) compared with 7.0 months (95% CI, 4.0-10.1 months) for ¹⁸FDG-PET/CT-positive patients. No differences in mPFS were found in relation to TTF1-value, histologic subtype, and presence of extrahepatic metastases. Conclusion: SSAs showed antitumor activity in terms of disease control rate and PFS and proved safe, even in patients with poor Eastern Cooperative Oncology Group status. ¹⁸FDG-PET/CT would appear to be a prognostic factor.