Lung neuroendocrine tumors (LNETs) or commonly referred as pulmonary carcinoids are a relatively rare group of tumors with an incidence of 0.2-2 cases per 100,000 population.1 With improvement in various diagnostic modalities and increased awareness, there is a linear rise in the incidence of LNETs. Depending on the location, LNETs are broadly classified into central LNETs and peripheral LNETs. Central LNETs which often involve main bronchi are symptomatic and detected early. However, peripheral lung NETs are asymptomatic and incidentally diagnosed. Functional/secretory LNETs are detected early due to secretion of various hormones and they comprise less than 10% of all LNETs. Most commonly secreted hormone is ACTH causing Cushing syndrome.2

Unlike non–small-cell lung carcinomas, grade is an important prognostic factor along with stage LNETs. Based on mitosis count and morphology, LNETs are divided into well differentiated grade I (typical carcinoid), grade II tumors (atypical carcinoid), large cell and small cell neuroendocrine carcinomas.3 In a retrospective evaluation of prognostic significance of Grade and TNM stage in LNETs, it was observed that 10-year disease specific survival for grade I LNETs with stage I-II was 95% and for stage III-IV was around 50%. On the other hand, 10-year DSS for grade II LNETs with stage I-II was 75% whereas it dropped to less than 20% for stage III-IV LNETs. This study concluded that along with grade, LNETs need to be staged correctly.4

Somatostatin receptors (SSTR) are a group of transmembrane G protein coupled receptors which are abundantly expressed on the neuroendocrine tumor cells.5 These receptors can be noninvasively imaged with the help of molecular imaging using Positron Emission Tomography coupled with CT scan (PET/CT). PET/CT using radiolabeled somatostatin analogues which targets SSTR has a very high sensitivity and diagnostic accuracy for the staging of LNETs.6 Similarly, somatostatin analogues i.e. octreotide is being used routinely for the treatment of LNETs.7 Recently, Peptide Receptor Radioligand Therapy (PRRT) with Lutetium177 (177LuDOTATATE) which is a somatostatin analogue, has shown survival benefit in NETs.8,9 PET/CT using radiolabeled somatostatin analogues and PRRT forms a unique Theranostics pair for the diagnosis and treatment of LNETs. Unfortunately, SSTR expression is not as common in LNETs as in GI NETS. Moreover, as the grade advances, the SSTR expression starts to decline in LNETs which becomes a major challenge in the management algorithm.10 Also, robust data in metastatic and recurrent settings is lacking. Hence, this narrative review is formulated with the aim to highlight the existing literature and explore the emerging trends in the management of LNETs with focus on Theranostics.