A lung carcinoid tumor is a type of malignant tumor made up of neuroendocrine cells, which are commonly found in the lungs. These cells produce hormones and neurotransmitters, functioning similarly to nerve cells. Sometimes, these cells grow rapidly and form small tumors known as carcinoid tumors. While these tumors can develop in various organs, only about 2 out of 10 carcinoid tumors are found in the lungs.

Lung carcinoid tumors are categorized into two types: typical and atypical.

• Typical Carcinoids: These account for about 9 out of 10 lung carcinoids. They grow slowly and rarely spread beyond the lungs.
• Atypical Carcinoids: These are less common but tend to grow more quickly and are more likely to spread beyond the lungs.

How Common are Lung Carcinoid Tumors?

Lung carcinoid tumors are quite rare, making up just 1% to 2% of all lung cancers. Each year, around 2,000 to 4,500 new cases are diagnosed in the United States. Carcinoid tumors are more often found in other parts of the body, such as the digestive tract. People with lung carcinoid tumors tend to be younger than those with other types of lung cancer.

What Causes Lung Carcinoid Tumors?

The exact cause of lung carcinoid tumors is unknown. They are not clearly linked to smoking, air pollution, or specific chemicals. However, certain factors may increase the risk:

• Ethnicity and Gender: They are more common in people of Caucasian descent and are slightly more prevalent among women.
• Genetics: People with a rare inherited disorder called multiple endocrine neoplasia type 1 (MEN1) have a higher risk of developing lung carcinoids.

What are the Symptoms of Lung Carcinoid Tumors?

Many people with lung carcinoid tumors, over 25%, do not show any symptoms. Often, these tumors are discovered incidentally during tests for other health issues, such as chest X-rays for lung infections.

When symptoms do occur, they typically include:

• Coughing or Wheezing: Sometimes with blood.
• Post-obstructive Pneumonia: Caused by larger tumors obstructing air passages.

Carcinoid syndrome is rare in lung carcinoid tumors, but when it occurs, symptoms might include:

• Facial flushing and redness
• Wheezing, shortness of breath, or asthma-like symptoms
• Weakness
• High blood pressure
• Weight gain
• Increased body and facial hair (hirsutism)

It's important to consult a healthcare provider to determine the exact cause of these symptoms.

How are Lung Carcinoid Tumors Diagnosed?

Diagnosing lung carcinoid tumors usually involves several steps:

• Medical History and Physical Examination: Your healthcare provider will ask about your medical history and symptoms.
• Imaging Tests: Chest X-rays and computed tomography (CT) scans are commonly used. CT scans provide detailed images of the lungs and can identify small tumors and any spread to other organs.
• Blood and Urine Tests: These can measure hormone levels and substances related to carcinoid tumors.
• Biopsy: A small tissue sample from the tumor may be examined under a microscope. Biopsies can be nonsurgical (such as bronchoscopy) or surgical.

How are Lung Carcinoid Tumors Treated?

Treatment depends on factors like the tumor's size, location, and the patient's overall health. The main treatments are surgery and radiation therapy.

• Surgery: This is often the preferred method, especially if the tumor hasn't spread. Surgical options include lobectomy (removal of a lung lobe), pneumonectomy (entire lung removal), and sublobar resection (removal of part of a lobe). Lymph node dissection may also be performed.
• Radiation Therapy: High-energy radiation is used to destroy cancer cells. External-beam radiation therapy is typically used, but internal radiation (brachytherapy) may be an option in some cases.

For treating carcinoid syndrome, the drug Sandostatin® (octreotide) can help regulate hormone production. Chemotherapy might be used if the tumor has spread to other organs. An mTOR inhibitor called everolimus (AFINITOR®) may be used before chemotherapy, and peptide radioligand therapy might be considered for metastatic disease.

What is the Outlook for Patients with Lung Carcinoid Tumors?

The prognosis is generally good. The five-year survival rate for typical carcinoid tumors is between 85% and 95%, while for atypical carcinoids, it's between 50% and 60%. Survival rates are higher for patients whose tumors have not spread.

Regular follow-up visits with healthcare professionals are essential because carcinoid tumors can recur. Patients should report any unusual symptoms, such as breathing difficulties, unexplained weight loss, or pain, to their healthcare provider promptly for evaluation and care.