Approximately 20% of all primary lung tumors are neuroendocrine (Hung 2019), including:
- Typical carcinoid (TC)
- Atypical carcinoid (AC)
- Small cell carcinoma (SCC)
- Large cell carcinoma (LCNC)
Classification of Lung NETs
“When we are classifying lung NETs we want to make one basic distinction,” said Suki Padda, MD, Stanford University, “Is this a well-differentiated lung NET, which includes low-grade typical carcinoid, or intermediate grade atypical carcinoid, or is this a poorly differentiated lung NET and that includes SCC and LCNC?” The outlook for each is different.
Classifications of lung neuroendocrine tumors
Grade
Prevalence (% of all lung tumors)
Associated with smoking
Overall survival at 5 years
Typical Carcinoid
Atypical Carcinoid
Low
Intermediate
1-2%
∼0.2%
No
No
>90%
50-80%
Small Cell Carcinoma
Large Cell
Neuroendocrine
Carcinoma
High
High
10-15%
2-3%
Yes
Yes
5%
15-40%
Source: Hung 2019
“Large cell neuroendocrine carcinoma and small cell carcinoma are not well differentiated and are very aggressive; these are the ones that we are going to give systemic therapy, such as chemotherapy,” said Nagla Karim, MD, PhD, University of Cincinnati. “The typical and atypical carcinoid are well differentiated are not very aggressive.”
Diagnosing Lung NETs
As with other NETs, the diagnosis of lung NETs can be challenging. Some patients do not show any signs of illness. Those with symptoms, such as coughing, wheezing, or tightness in the chest, may be diagnosed with more common illnesses, such as asthma. Since lung NETs develop in hormone-producing cells, a few patients experience symptoms unrelated to the lungs, such as diarrhea or flushing in the face.
Lung NET presentations from NET patient and caregiver conferences.
Treatment for Lung NETs
A lack of consensus among leading treatment guidelines complicates the diagnosis of lung NETs. (Hendifar 2017) There are also different recommendations about the need for chemotherapy and/or radiation in early-stage patients who have undergone surgery. (Hendifar 2017, Ramirez 2017) An individual’s treatment will be based on a range of factors including disease classification, stage, lymph node involvement, and tumor biomarkers. Robert Ramirez, DO, Ochsner Medical Center, stresses the importance of a multidisciplinary treatment team for lung NETs to obtain an accurate diagnosis and avoid unnecessary procedures. NETRF has compiled a list of multidisciplinary team-based programs.
The options commonly considered by a treatment team may include:
(Ramirez 2017; NCCN Guidelines Version 3.2017)
- Surgery
- Somatostatin analogs
- mTOR pathway inhibitors
- Vascular treatments
- Chemotherapy (may be a combination of therapies)
- Radiotherapy, such as PRRT
- Radiation (radiofrequency ablation, stereotactic body radiation therapy or SBRT)
- Interventional radiology (embolization)
Learn more about lung NETs