Carcinoid Tumors

Carcinoids on Stage
Doctors have a system to describe the severity of a carcinoid tumor: the TNM Staging System. T is for tumor—its size and rate of spreading in the lung. N is for nodes, as in lymph nodes—has the cancer spread to them? M is for metastasis—how much and how far has the cancer spread to “distant sites” (other organs)? Scores are assigned to each. Of course, the lower the score, the less severe the ailment.

What are Carcinoid Tumors?

Carcinoid tumors are fairly rare, slow-developing cancerous growths in the lungs that seldom spread to other parts of the body. Around 1,700 cases are diagnosed each year in the United States. Carcinoid tumors are twice as likely to affect whites as minority groups, and twice as common in women as in men. Older people have a greater chance of developing these tumors than younger people—the average age at diagnosis is 60.

In their early stages, most carcinoid tumors do not produce any symptoms. But because they grow and spread very slowly, most are identified in time for treatment to have a good success rate. Around 4 out of 5 carcinoid tumor patients survive for at least 5 years after diagnosis, and 7 out of 10 survive for more than 10 years. Patients whose tumors are larger, have a relatively faster growth rate (called atypical), or have spread to the lymph nodes will have a worse prognosis.

The Mechanics of Carcinoid Tumors

Like most cells in the body, lung cells sometimes go through certain changes that prompt them to grow excessively. These accumulating cells can turn into tumors of one kind or another. The cells that turn into carcinoid tumors are neuroendocrine cells. When functioning normally, these particular cells produce hormones to help control blood and air flow in the lungs.

Carcinoid tumors are divided into two types based on their appearance:

Typical carcinoids grow slowly and rarely spread beyond the lungs. Nine of every 10 carcinoid tumors are classified typical.
Atypical carcinoids have more cells in the process of dividing at any given time, so they grow faster and are more likely to spread elsewhere. But they are a small percentage of these tumors.

Carcinoid tumors also are classified based on where they appear in the lung:

Central carcinoids form in the center of the lung, in the walls of the larger airways.
Peripheral carcinoids form toward the edges of the lung, in the narrower airways.

This positional distinction is important because it will affect which symptoms (if any) a patient will experience, as well as dictate treatment options.

Nearly all central carcinoids are of the typical variety. When atypical carcinoids do appear, they are likely to be peripheral.

Symptoms of Carcinoid Tumors

Carcinoid tumors can produce the following symptoms:

Cough
Chest pain
Wheezing
Asthma
Blood-tinged sputum

If one of these tumors grows to the point where is begins blocking a larger air passage, the patient might develop a lung infection called post-obstructive pneumonia. Normally, the doctor will suspect a tumor when the antibiotics given to treat the pneumonia fail to relieve it.

On rare occasions, a carcinoid tumor produces hormone-like substances that enter the bloodstream. The illness that results is called carcinoid syndrome and brings on the following symptoms:

A flushed face for long durations
Sweating
Diarrhea
Accelerated heartbeat

Some carcinoid tumors produce a different hormone-like substance (ACTH) that, in turn, stimulates the adrenal gland. The symptoms of this tumor-related condition include:

Weight gain
General weakness
Increased body and facial hair
Secondary diabetes

Causes of Carcinoid Tumors

Very little is known about what might cause carcinoid tumors. Scientific studies haven’t even uncovered any reliable risk factors. This is one lung cancer that has no relationship to smoking or workplace fumes. There’s general agreement that these tumors are somehow linked to the glands under the surface of the lung’s large air passages, which produce the neuroendocrine cells. But researchers haven’t figured out how the cells turn into carcinoid tumors.

Diagnosing Carcinoid Tumors

Like most other lung cancers, doctors rely primarily on non-invasive chest x-rays and the more detailed CT (computed tomography) scans to locate and initially identify carcinoid tumors. For more precise information, a doctor might retrieve and analyze a sample of the patient’s sputum to determine the type and condition of cells present in the lungs. Retrieval of some tumor cells from the chest cavity using a long surgical needle is another typical procedure.

Treating Carcinoid Tumors

With some variations, treatment options for carcinoid tumors tend to be very much like the treatment options for other cancers of the lungs and chest. They include:

Surgery—best for localized tumors and a good success rate overall
Radiation therapy—a widely chosen course of action when circumstances eliminate surgery as an option
Clinical trials—patients become part of treatment programs using promising new drugs or procedures
Alternative treatments—vitamin and herb regimens, acupuncture and other non-traditional treatments are of interest to a lot of people, but have not produced significant beneficial results

In one interesting departure, doctors have found that chemotherapy is ineffective against carcinoid tumors and, therefore, is virtually never recommended.