Lung carcinoid tumors make up less than 5 percent of all lung cancers. Lung carcinoid tumors tend to grow slower than other types of lung cancer. They are also known as lung neuroendocrine tumors (NETs) because they are made up of neuroendocrine cells (cells that receive messages from the body and release hormones).1,2
What are neuroendocrine tumors (NETs)?
Neuroendocrine cells are part of the diffuse neuroendocrine system found throughout the body. The cells are similar to both nerve cells and endocrine cells. Neuroendocrine cells produce hormones like adrenaline, which in the lungs, helps control airflow and blood flow. It is believed that neuroendocrine cells may detect the levels of carbon dioxide and oxygen in the air and release chemical messages to help the lungs adjust to these changes.1
Types and staging of lung carcinoid tumors
Doctors determine the treatment for lung carcinoid tumors based on the type of tumor (typical or atypical) and the extent of the disease. Typical carcinoid tumors grow slowly and rarely metastasize (spread) beyond the lungs. Typical carcinoid tumors make up approximately 90 percent of lung carcinoid tumors. Atypical carcinoid tumors grow faster than typical carcinoid tumors and have an increased chance of metastasis. Atypical carcinoid tumors are less common than typical carcinoid tumors.1,2
The extent of the disease for lung carcinoid tumors is characterized as resectable tumors (those that can be removed with surgery) and unresectable tumors (those that can’t be completely removed with surgery).1
Surgical options for lung carcinoid tumors
For resectable lung carcinoid tumors, surgery is the main treatment and may be the only treatment needed. However, patients are evaluated to ensure their overall health can withstand the surgery. The types of surgery for lung carcinoid tumors include:1,3
- Pneumonectomy – removal of an entire lung
- Lobectomy – removal of a portion (lobe) of the lung; if two lobes are removed, it is referred to as a bilobectomy
- Wedge resection – a small, wedge-shaped portion of the lung is removed
- Sleeve resection – removal of sections of the airway above and below the tumor along with the tumor itself; the sections of the airway are then reconnected
- Lymph node dissection – removal of some of the nearby lymph nodes to determine if the cancer has spread
Non-surgical treatment options
For unresectable tumors or for patients who cannot tolerate surgery, treatment options include radiation therapy and some form of systemic therapy (treatment that reaches the entire body). Radiation therapy uses high-energy rays targeted on the tumor to kill cancer cells. Systemic treatments for lung carcinoid tumors include chemotherapy, targeted therapy, or another class of drugs, somatostatin analogs. Chemotherapy is often not very successful in treating lung carcinoid tumors, but can be an option when tumors have spread beyond the lungs or the cancer is resulting in severe symptoms for the patient.1,3
Somatostatin analogs are drugs that slow down the hormone production in the body. Because lung carcinoid tumors are made up of neuroendocrine cells, which produce hormones, somatostatin analogs can be an effective treatment to help reduce symptoms and potentially shrink the tumor.4
- Octreotide (Sandostatin®) was the first somatostatin analog to be developed. In clinical trials, octreotide has demonstrated effectiveness in treating the hormone-related symptoms and extending progression-free survival time (length of time where the patient lives with the cancer without the cancer worsening), however, it does not cure the cancer.
- Lanreotide (Somatuline®) works similarly to octreotide and results from clinical trials have shown similar effectiveness in reducing symptoms and slowing the progression of tumors.1,5
Targeted therapies for lung carcinoid tumors
Targeted drugs are medications that specifically focus on unique characteristics or mutations in cancer cells. Two targeted therapies with potential use for lung carcinoid tumors are sunitinib (Sutent®) and everolimus (Afinitor®).
Sunitinib is currently approved for the treatment of neuroendocrine tumors that originate in the pancreas and is being studied for its effectiveness in lung neuroendocrine tumors. Everolimus was approved by the U.S. Food and Drug Administration (FDA) for the treatment of lung neuroendocrine tumors that are unresectable, locally advanced or metastatic (spread to distant sites in the body). The drug gained approval after patients in a clinical trial treated with everolimus experienced a longer progression-free survival than patients receiving placebo.1,6