Lung Carcinoid Tumor

Reviewed by: HU Medical Review Board | Last reviewed: January 2017.

Lung cancer is a term that refers to any cancer that begins in the lungs. There are several types and variations of lung cancer. 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 cells?

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

Classification of lung carcinoid tumors

Lung carcinoid tumors can be classified into two types:

  • 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 location of where lung carcinoid tumors form is also used in classification:

  • Central carcinoids begin in the bronchi (air ways) and may also be called broncopulmonary carcinoids.
  • Peripheral carcinoids (outer regions of the lungs) begin in the bronchioles that branch off from the right and left bronchi.1,2

Risk factors for developing lung carcinoid tumors

Unlike other lung cancers, smoking is not thought to be linked with lung carcinoid tumors. Factors that increase a person’s risk of developing a lung carcinoid tumor include:

  • Being a woman – lung carcinoid tumors occur more frequently in women than men
  • Ethnicity – lung carcinoid tumors occur more frequently in whites than in other ethnic groups
  • Age – these tumors are usually found in people around age 60
  • Family history – having family members who had lung carcinoid tumors increases the risk
  • Multiple endocrine neoplasia type 1 (MEN1) – this inherited syndrome increases the risk for tumors in certain endocrine organs and increases the risk for lung carcinoid tumors 1

Other neuroendocrine tumors

Because neuroendocrine cells are found throughout the body, neuroendocrine tumors can develop anywhere in the body. Another common site for neuroendocrine tumors is in the gastrointestinal system. These tumors are called gastrointestinal neuroendocrine tumors, and while they have some similar characteristics to lung neuroendocrine tumors, they are a different cancer.1

Symptoms of lung carcinoid tumors

Some people with lung carcinoid tumors have no symptoms, and the cancer may be found by medical tests done for other reasons. However, the majority of people with lung carcinoid tumors do experience symptoms, including

Hormonal symptoms

Because lung carcinoid tumors are made up of neuroendocrine cells, which produce hormones, some people with lung carcinoid tumors experience carcinoid syndrome, which produces symptoms such as facial flushing, diarrhea, wheezing, and a rapid heartbeat. Gastrointestinal carcinoid tumors are more likely to cause these symptoms than lung carcinoid tumors.1

Survival rates

Survival rates are determined based on the previous outcomes of people who survive a specific amount of time after diagnosis. In lung cancer, as in other types of cancer, experts use “5-year survival rate,” or the percentage of people who survive at least five years after diagnosis, as a marker for lung cancer prognosis (projected outcome). It is important to remember that many people live beyond this 5-year marker after diagnosis of lung cancer and these statistics do not necessarily predict what will happen for a particular individual.

The 5-year survival rate for patients with typical lung carcinoids is between 85-90 percent, and the 5-year survival rate for patients with atypical lung carcinoids is between 50-70 percent.1

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