Carcinoid Tumor in the Lung: Symptoms, Diagnosis, and Treatment

Lung carcinoid tumors form in the small, hormone-producing cells of the lungs, known as neuroendocrine cells. These tumors are relatively rare and generally grow at a slower rate than other lung cancers, said George Chaux, MD, board-certified interventional pulmonologist and medical director of Interventional Pulmonary at Providence Saint John’s Health Center in Santa Monica, California.

While lung carcinoid tumors can occur in anyone, they are more common in people between the ages of 45 and 55, according to the American Cancer Society.

There are two main types of lung carcinoid tumors, typical and atypical:

• Typical lung carcinoids: These tumors grow slowly and rarely spread to other parts of the body. Most lung carcinoids fall within this category and are usually treated with surgery.

• Atypical lung carcinoids: These tumors grow more quickly than typical lung carcinoids. They are considered intermediate-grade malignancies and have a higher risk of recurrence, metastases, and lymph node spread, said Abigail Fong, MD, MBA, thoracic surgeon at City of Hope National Medical Center in Duarte, California. Only around 10% of lung carcinoids are considered atypical.

Depending on the tumor's location, people with lung carcinoid tumors may not experience symptoms, said Dr. Chaux. When symptoms do occur, they may include:

• New onset cough

• Shortness of breath

• Chest pain

• Wheezing

• Coughing up blood

• Recurrent pneumonia or bronchitis

Airway obstruction, which can cause difficulty breathing and may lead to pneumonia or other complications, is another possible sign of lung carcinoid tumors, Dr. Chaux said. Imaging tests may detect these tumors before symptoms appear.

Carcinoid tumors arise in cells that produce hormones, like serotonin and histamine. People with carcinoid tumors can experience a collection of symptoms known as carcinoid syndrome from the excess production of these hormones, said Samuel J. Riney, MD, MS, a medical oncologist with Methodist Le Bonheur Healthcare. This may include:

• Facial flushing

• Shortness of breath

• High blood pressure

• Weight gain

• Hirsutism (male pattern hair growth in women)

• Asthma-like symptoms

Experts don't know what causes these tumors to develop. Like other forms of lung cancer, exposure to environmental toxins and smoking may play a role. However, typical carcinoids are not thought to be strongly associated with smoking, according to the American Cancer Society.

They are believed to develop from the neuroendocrine cells responsible for producing hormones that regulate digestion, blood sugar, and other bodily functions. DNA mutations in these cells cause them to divide and grow uncontrollably. When this happens, clusters of abnormal cells can form and develop a carcinoid tumor.

Most carcinoid tumors are located in the gastrointestinal tract, but they can also develop in the lungs, pancreas, kidneys, and other organs. According to the National Institutes of Health, lung carcinoids make up less than 1% of all lung cancers.

Some factors can increase your risk of developing a lung carcinoid tumor, including:

• Age: These tumors are most commonly diagnosed in people between the ages of 45 and 55, although they can occur at any age.

• Gender: They are more common in women than men, according to the American Cancer Society.

• Smoking: While smoking is not considered a significant risk factor for typical lung carcinoids, it may increase the likelihood of developing atypical lung carcinoids.

• Family history: Having a first-degree relative with lung cancer or multiple relatives with lung cancer puts you at a higher risk of lung cancer, though this type of cancer is usually sporadic and not inherited.

• Other medical conditions: People with rare genetic syndromes, such as multiple endocrine neoplasia type 1 (MEN1), are at higher risk of neuroendocrine tumors, said Dr. Fong. MEN1 is a hereditary condition that causes tumors in multiple parts of the body.

If you experience symptoms of a lung carcinoid tumor, your doctor will likely start with a physical exam to assess your general health and any risk factors you may have.

During the physical exam, your doctor will listen to your lungs for abnormal sounds or wheezing and may order pulmonary function tests to assess lung function. They will also ask about your medical history and any previous chest X-rays or imaging studies.

Imaging tests are a standard method for diagnosing lung tumors or other abnormalities. Your doctor may order a chest X-ray or CT scan. However, most typical and atypical carcinoid tumors are found incidentally during imaging for another concern, like pneumonia or chest pain, said Christian Campos, MD, thoracic surgeon with Beth Israel Deaconess Hospital-Plymouth and lecturer in surgery at Harvard Medical School.

A radionuclide lung scan is a nuclear imaging test that can help detect small tumors or assess the extent of cancer spread. This procedure involves injecting a small amount of radioactive material into your bloodstream and taking images of your lungs using a special camera. Depending on the type of lung scan, it may involve looking at airflow, blood flow, or both.

Sputum cytology is another test your doctor may recommend. It involves collecting a sample of mucus from your lungs and examining it under a microscope for cancer cells.

A biopsy is essential for diagnosing a carcinoid tumor, said Jimmy Johannes, MD, pulmonologist and critical care medicine specialist at MemorialCare Long Beach Medical Center in Long Beach, California. Your doctor will take a tissue sample from the lung tumor or a lymph node using one of several methods:

• Bronchoscopy: A thin, flexible tube with a light and camera is inserted through your nose or mouth and down into your lungs. This allows your doctor to view and collect tissue samples from inside your lungs.

• Needle biopsy: A hollow needle is inserted through your skin and into the lung tumor, guided by imaging tests like a CT scan. This procedure can also be done during bronchoscopy.

• Mediastinoscopy: A larger, rigid tube is inserted through a small incision in your neck to collect lymph node samples.

• Endobronchial ultrasound (EBUS): This procedure combines bronchoscopy and an ultrasound probe at the end of the scope. Your doctor can visualize and sample lymph nodes using this method.

If the biopsy shows cancerous cells, your doctor may order additional tests to determine the stage of your lung cancer and develop a treatment plan.

Lung carcinoid tumors are classified into stages based on the size and location of the tumor, as well as whether it has spread to other parts of the body. There are a few different staging methods, but the most common is the TNM system, which stands for:

• Tumor (T): The size and location of the primary tumor

• Node (N): Whether cancer has spread to nearby lymph nodes

• Metastasis (M): Whether cancer has spread to distant organs or tissues

You may also see the classic stage 0 through IV system used for carcinoid tumors:

• Stage 0: Cancer cells are only found in the top layer of cells lining the airways and have not spread.

• Stage I: The tumor is still confined to one lung and has not spread to lymph nodes.

• Stage II: The tumor may be larger and has spread to nearby lymph nodes or structures like the chest wall or diaphragm.

• Stage III: The cancer has spread to multiple lymph nodes on either side of your chest but not outside the chest.

• Stage IV: Cancer has spread beyond the lungs and into other organs or tissues.

The stage helps determine which treatment options may be most effective for killing the cancer cells and controlling symptoms.

Surgery is often the first line of treatment, particularly if the tumor is confined to one area, said Dr. Johannes. Depending on the size and location of the tumor, your surgeon may remove only a portion of your lung or the entire affected lobe. In some cases, they may also remove nearby lymph nodes to reduce the chances of cancer recurrence.

Chemotherapy and radiation therapy help destroy cancer cells and shrink tumors. Your doctor may recommend one of these treatments after surgery to ensure there are no remaining cancer cells. If the tumor is too large or in a difficult location to remove with surgery, your doctor may use these treatments as the primary form of treatment. However, Dr. Johannes said it is "not considered a curative treatment."

Targeted therapy is a newer treatment option that targets specific genes, proteins, or other factors that help cancer cells grow. These medications can be taken orally or given through an IV and are particularly helpful for certain types of lung carcinoid tumors. Targeted therapy may also be combined with other treatments.

Somatostatin analogs are a type of hormone therapy that helps control symptoms and slow tumor growth by blocking the release of hormones from the tumor. They benefit people whose tumors produce hormones that cause symptoms like facial flushing or diarrhea. Examples include octreotide (Sandostatin) and lanreotide (Somatuline).

Watchful waiting may also be an option for some people with slow-growing carcinoid tumors. Your doctor will monitor your condition closely and only start treatment if the tumor begins to grow or cause symptoms.

It may not be possible to prevent lung carcinoid tumors, but you can lower your risk of lung cancers by making healthy lifestyle choices. Avoiding tobacco smoke, limiting exposure to harmful chemicals and pollutants, eating a healthy diet with fruits and vegetables, and exercising may help.

As experts learn more about the causes and risk factors of lung carcinoid tumors, it may become possible to prevent them. Since smoking may play a role in atypical carcinoid tumors, quitting smoking is one of the best things you can do to lower your risk.

Treatment, especially for small, early-stage lung carcinoid tumors, is often effective. Your doctor will recommend follow-up appointments to continue monitoring your lungs, even after the cancer is gone. Since there is a chance of recurrence, follow-ups are essential for catching any changes early.

According to Dr. Riney, typical carcinoids have a better long-term prognosis than atypical carcinoids because they are generally slower-growing and less likely to spread. Still, there's no way to predict how exactly your cancer will behave – your health and medical history will likely play a role in your outlook.