Lung carcinoid tumors

Lung carcinoid tumors are tumors made of neuroendocrine cells. Neuroendocrine cells produce chemical messengers called hormones, hormone-like substances or neurotransmitters.

Carcinoid—or neuroendocrine—tumors may develop throughout the body. Most form in the gastrointestinal tract, but about 30 percent originate in the airways of the lungs, according to the American Society of Clinical Oncology (ASCO). These tumors are malignant. Most grow very slowly, but some may grow more quickly and spread to other parts of the body.

Lung carcinoid tumors are rare, accounting for 1 to 2 percent of all lung cancers, according to the American Cancer Society (ACS). Fewer than 4,500 cases are diagnosed in the United States every year. Lung carcinoid cancers tend to occur at an earlier age than other cancers.

Lung carcinoid tumor types

There are two types of carcinoid tumors:

• Typical carcinoids are more likely to grow slowly and not spread outside the lungs. They make up about 90 percent of lung carcinoid tumors, according to the ACS.
• Atypical carcinoids grow more quickly and may spread to other parts of the body.

Lung carcinoid tumors may also be classified based on where they occur in the lung:

• Central tumors, the more common type, are found in the large airways near the central part of the lungs.
• Peripheral tumors form in smaller airways toward the outer parts of the lung.

What are the symptoms of lung carcinoid tumors?

A lung carcinoid tumor doesn’t typically cause symptoms unless it grows large enough to block an airway. This is more common with atypical type carcinoids that grow quickly.

Lung carcinoid tumors that block an airway may cause these symptoms:

• Persistent cough, which may produce phlegm or blood
• Shortness of breath
• Wheezing
• Chest pain
• Lung infection (pneumonia)

Tumors that produce hormone-like substances are usually gastrointestinal carcinoids, but lung tumors may sometimes secrete these substances. Hormone substances may spread through the body and cause symptoms that include flushing of the chest and face, diarrhea and shortness of breath.

What causes lung carcinoid tumors?

The cause of lung carcinoid tumors is unknown, and there are no avoidable risk factors. Smoking doesn’t appear to cause this condition.

These tumors are more common among white people than among other ethnic groups, according to the Genetic and Rare Diseases Information Center. Anyone with a family history of an inherited disease called multiple endocrine neoplasia type 1 (MEN1) also may be at higher risk.

ASCO reports that most patients with typical type carcinoids are diagnosed at about age 45. The atypical, faster-growing type is usually diagnosed around age 55. These tumors rarely occur in children.

How are lung carcinoids diagnosed?

Because typical carcinoids are slow-growing and don’t typically show symptoms, they may be diagnosed during a procedure or imaging study for an unrelated lung condition. Diagnosis of atypical carcinoids may start with symptoms of a blocked airway.  The diagnostic process may involve imaging studies, blood and urine tests, and a biopsy.

How is a lung carcinoid tumor treated?

Once all diagnostic tests are completed, the tumor is staged. The cancer stage is based on the tumor’s growth and size. Treatment for a lung carcinoid depends on the type (typical or atypical) and the stage of the cancer.

According to the ACS, lung carcinoid tumors are often identified as:

• Resectable stage carcinoid tumors, which may be treated with surgery alone
• Unresectable stage tumors, which can't be completely removed or treated with surgery (Additional options for these tumors may include radiation, chemotherapy, or clinical trials.)

Survival rates for a lung carcinoid tumor

Survival rates depend on the spread of the lung carcinoid tumor. A relative five-year survival rate is the percentage of people still alive five years after diagnosis. For patients with lung carcinoid tumors that haven’t spread outside the lung, the five-year survival rate is 98 percent, according to the ACS. The rates are 87 percent for patients whose cancer has spread outside the lung but not to distant sites, and 58 percent for those with tumors that have spread distantly in the body.