Ga-68 somatostatin receptor PET/CT in the management of neuroendocrine tumors of the lungs

Objectives Neuroendocrine tumors of the lungs (L-NET) are rare and comprise about 1-2% of all lung malignancies. The aim of this study was to investigate the role of Ga-68 Somatostatin Receptor PET/CT for detection of metastases (mets) after the initial diagnosis.

Methods In this retrospective analyses we found 17 L-NET patients (F:M 11:7; age at the time of first diagnosis; 18-74 years) in our database. Ga-68 Somatostatin Receptor PET/3-Phase contrast-enhanced CT (using Ga-68 DOTA-TATE/- or TOC) was performed in accordance with the EANM procedure guidelines.

Results Out of the 17 patients, only 7 patients (pts) could be classified as typical (n=4) or aytpical (n=3) L-NET. Two pts had large cell L-NET and one had familial MEN1 syndrome (L-NET with pancreatic NET-pNET). Overall, 15 pts underwent surgery. Four pts had liver mes (2 SR + / 2 SR-), 5 had lymph node mets (all SR+), 3 had bone mets, 3 had lung mets(2 SR+/1 SR-), one had a local residue. In the MEN1 pts the primary lung t as well as the pNET was SR+. One pts presented with metastases 22 years after the first diagnosis. The other pts having metastases and / or local residual tumor presented at 1-10 years after the first diagnosis and R0 operation. Three atypical L-NET pts presented no or only faintly somatostatin receptor positive lesions. One pts with atypical NET showed several strongly somatostatin receptor positive bone metastases and was treated with Peptide Receptor Radionuclide Therapy.

Conclusions Ga-68 Somatostatin Receptor PET/CT plays a significant role in the management of most of the typical L-NET and should be used for follow-up even after 10 years of surgery. In this short series, atypical L-NET appeared to have mostly somatostatin receptor negative lesions; a combination of PET/3-phase CT should be used for complete restaging