Lung neuroendocrine tumours (NETs) account for 25– 30% of all NETs (Figure1a), constituting the largest subgroup of NETs outside the gastroenteropancreatic (GEP) tract. In general, they represent 1% of all cases discussed at lung multidisciplinary team (MDT) meetings, and altogether they form up to 2% of all lung cancers. Incidence has dramatically increased over the past three decades from 0.3 per 100 000 in 1973 to most recently 1.49 per 100 000 reported in the United States (US) Surveillance, Epidemiology and End Results (SEER) 18 (2000– 2012) (Figure 1b), making it the most rapidly increasing subgroup of NETs by approximately 6% per year. It is believed that the disease remains largely undiagnosed in the general population. Thus, it is predicted to continue rising with improved aware ness among respiratory physicians who are often the first point of referral and also with better diagnostic tools now available for this disease entity.
Fig1. Epidemiological representation of neuroendocrine tumours (NETs). (a) Incidence of NETs by anatomical distribution. (b) Graph showing progressive increase in incidence of NETs, particularly lung, small intestine, and rectum NETs. Panel (a) reproduced with permission from Bodei L, Ćwikla JB, Kidd M, Modlin IM. The role of peptide receptor radionuclide therapy in advanced/ metastatic thoracic neuroendocrine tumors. J Thorac Dis. 2017;9(Suppl 15):S1511- S23. Panel (b) reproduced with permission from Dasari A, Shen C, Halperin D, Zhao B, Zhou S, Xu Y, et al. Trends in the Incidence, Prevalence, and Survival Outcomes in Patients With Neuroendocrine Tumors in the United States. JAMA Oncol. 2017;3(10):1335– 42. Copyright © 2017, American Medical Association.
The peak incidence for lung NETs is observed in the fourth to sixth decade of life. There is a slight female preponderance and they tend to be more common among white Caucasians, and are relatively rare in other ethnicities including among Blacks, Asians, or Hispanics. Importantly, lung NETs are the most common primary lung neoplasms diagnosed in children and late adoles cents, particularly typical carcinoid (TC). Lung NETs are not usually associated with a history of smoking, except in large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC) which develop in heavy smokers.
