Neuroendocrine Lung Tumors: Types, Symptoms, Causes, Diagnosis, and Treatment

What Are Neuroendocrine Lung Tumors?

Neuroendocrine lung tumors are a rare kind of cancer that happens in the specialized lung cells called neuroendocrine cells. These are specialized cells that exhibit characteristics of both nerve and hormone-producing cells. Though these kinds of tumors may develop anywhere in the body, the lung is one of the most common sites after the digestive tract. Neuroendocrine lung tumors are said to cause 1 to 2 percent of all lung cancers. These may develop slowly and be curable by surgery, though others may develop more rapidly and spread to other tissues and organs.

What Are the Types of Lung Carcinoid Tumors?

The following are the types of lung carcinoid tumors:

• Typical Carcinoids:

These tumors constitute nine out of 10 lung carcinoids. They tend to grow slowly, and their spread beyond the lungs is rare.

• Atypical Carcinoids:

These tumors are very rare and grow faster than typical lung carcinoids. There is a great probability that these tumors will spread beyond the lungs. Lung carcinoid tumors can also be classified based on their location. Central carcinoids are those that develop in the walls of the large airways of the lungs. Peripheral carcinoids develop near the edges of the lungs, in the smaller airways. The central and peripheral carcinoids are mostly typical.

• Small Cell Lung Cancer (SCLC):

Small-cell lung cancer is the most common type of neuroendocrine tumor. It is considered to be aggressive and of high grade and is more likely to metastasize (spread) to other regions. SCLC not only causes cancer in neuroendocrine cells but also in the submucosal lining of the airways.

• Large Cell Lung Carcinoma (LCC):

LCC is a kind of non-small cell lung cancer (NSCLC). These, in rare cases, cause neuroendocrine lung cancer. LCC can be differentiated from SCLC by its size and is also considered high-grade due to its increased metastatic potential.

Are Carcinoid Tumors of the Lung Common?

Lung carcinoid tumors are very rare and constitute just one to two percent of all lung cancers. About 2,000 to 4,500 new cases of lung carcinoid tumors are being diagnosed in the United States every year. Carcinoid tumors have an increased susceptibility to developing in other parts of the body, like the digestive tract, more than in the lungs. Those who develop carcinoid tumors of the lungs are usually younger than those who develop other types of lung cancer.

What Are the Causes of Neuroendocrine Lung Cancer?

Neuroendocrine tumors have the potential to divide and grow abnormally, resulting in the development of cancerous tumors. The tumors that develop in the lungs are called pulmonary neuroendocrine tumors. Besides the lungs, these tumors can develop in the liver, colon, pancreas, ovaries, rectum, breast, thymus, thyroid gland, testes, prostate gland, adrenal glands, and pituitary gland. Though the exact causes of the manifestation of neuroendocrine tumors are not clear, there are several associated risk factors, which are as follows:

• Small Cell Lung Cancer (SCLC) and Large Cell Lung Carcinoma (LCC):

The incidence of SCLC and LCC is strongly linked to cigarette smoking. About 95 % of individuals who suffer from this type of lung cancer are either current or former smokers. Occupational exposure to cancer-causing agents (carcinogens) and environmental pollutants are also some of the common risk factors. Men are more commonly affected by these tumors than women.

• Carcinoid Tumors:

The manifestation of carcinoid tumors is rarely linked to environmental pollution, smoking, or occupational exposure. Children and young adults may be affected by this type of tumor. This tumor has a female predilection, and more whites are affected. It is believed that family history and genetics play a role in the manifestation of carcinoid tumors. Carcinoid tumors are linked with several genetic syndromes, like multiple endocrine neoplasia type 1 (MEN1- a hereditary condition linked with tumors of the endocrine glands).

What Are the Symptoms of Neuroendocrine Lung Cancer?

Neuroendocrine lung tumors may not cause any noticeable symptoms until they grow larger or spread. When this happens, the symptoms may mimic those of asthma. The symptoms of neuroendocrine lung cancer are as follows:

• A cough that does not resolve and which varies in intensity throughout the day.
• Fatigue.
• Coughing up small quantities of blood.
• Pain in the chest or shoulders.
• Frequent chest infections like pneumonia, or an infection that is unresponsive to treatment.
• Shortness of breath.

How Can Neuroendocrine Lung Tumors Be Diagnosed?

Not all diagnostic tests are employed in all individuals to diagnose neuroendocrine lung tumors (NET). The following factors are considered while choosing a diagnostic test:

• The type of tumor that is suspected.
• The age and overall health of the individual.
• The signs and symptoms.
• The results of previous medical tests.

A majority of lung NETs are diagnosed unexpectedly during medical procedures or imaging tests performed for other reasons. If NET is suspected, the physician will perform a complete physical examination and enquire about the individual's family and medical history. The following are a few diagnostic tests that are done to diagnose lung NET:

• Biopsy:

For a biopsy, a small amount of tissue is removed from the individual to be examined under a microscope. A biopsy is considered to be the only method of arriving at a definitive diagnosis, though other tests may suggest the possibility of cancer.

• Bronchoscopy:

It is a type of endoscopy in which a thin, flexible, lighted tube called a bronchoscope is used to visualize the airways and lungs. In case an abnormality is detected, a biopsy will be performed.

• Endobronchial Ultrasound:

In this procedure, sound waves are utilized to produce an image of the internal organs. Endobronchial ultrasound can detect enlarged lymph nodes, enabling the physician to identify a tumor or determine the stage of the disease.

• Nuclear Medicine Imaging:

In this procedure, a small amount of a radioactive tracer is injected into the patient’s vein. The body is then scanned to detect where the radioactive drug has accumulated in the body.

• Other Tests:

X-ray, CT (computed tomography), MRI (magnetic resonance imaging), blood and urine tests.

How Are Neuroendocrine Lung Cancers Treated?

Neuroendocrine lung cancers are treated based on their size and location, symptoms, tumor type, extent of spread (if any), growth rate, and the individual’s overall health. Some of the common treatment modalities are as follows:

• Surgery:

Surgery or resection refers to the removal of the tumor along with some of the surrounding healthy tissue. Complete tumor removal is considered the standard treatment. Some of the common surgical options include sleeve resection, sub-lobar resection (wedge resection or segmentectomy), lobectomy (removal of a lung lobe), liver resection, lymph node dissection, and pneumonectomy (removal of an entire lung).

• Chemotherapy:

In chemotherapy, several types of drugs like Carboplatin, Temozolomide, Cisplatin, and so on are used to kill cancer cells.

• Somatostatin Analogs:

Somatostatin analogs inhibit the body's production of excess hormones. This may retard the growth of the tumor when cancer cells have migrated (metastasized) to other parts of the body.

• Targeted Therapy:

In targeted therapy, drugs are utilized to target certain proteins or genes to kill cancer cells.

• Radiation Therapy:

Radiation therapy utilizes high-energy X-rays or other particles to destroy cancer cells. The preferred radiation treatment for neuroendocrine lung cancer is external-beam radiation therapy, in which radiation is emitted from a machine outside the body.

Conclusion

Neuroendocrine lung tumors are rare cancers that develop from hormone-producing cells in the lung. These include slow-growing carcinoids and aggressive small-cell lung cancer. Neuroendocrine lung tumors are rare cancers that arise from lung cells that produce hormones. These include slow-growing carcinoids and aggressive small-cell lung cancer. If you have concerns about lung tumors, consulting a cancer specialist can provide further information and assistance.

Key Takeaways

• Neuroendocrine lung tumors are a rare form of lung cancer.
• Neuroendocrine lung tumors include carcinoid tumors, small cell lung cancer, and large cell neuroendocrine carcinoma.
• The symptoms may include coughing, chest pain, and shortness of breath.
• The treatment options include surgery, chemotherapy, targeted therapy, or radiation therapy.
• If you notice any persistent respiratory symptoms, you should seek early medical consultation.