Carcinoid Lung Tumors

Carcinoid lung tumors are an uncommon group of lung tumors, that develop from neuroendocrine cells. The neuroendocrine cells are in some respect like nerve cells and other ways like cells of endocrine (hormone-producing) glands.

• There are a few types of tumors that can neither be classified as benign (noncancerous) nor malignant (cancerous). Their clinical behavior falls between the two classifications of benign and malignant, and they have sometimes been called "midway" tumors. They were so named in an attempt to designate these tumors as midway between cancers and benign tumors. Among these rare tumors are carcinoid tumors.
• Carcinoid tumors have also been called "cancers in slow motion." Even though they have the potential for being malignant, they mostly tend to grow so slowly that people with carcinoid tumors usually live for many years (sometimes for a normal lifetime).
• Carcinoid lung tumors are an uncommon group of lung tumors, that develop from neuroendocrine cells. The neuroendocrine cells are in some respect like nerve cells and other ways like cells of endocrine (hormone-producing) glands. These cells are scattered throughout the body and can be found in different organs, for instance, the lungs, stomach, and intestines. These neuroendocrine cells can form growths (tumors) in many different organs but usually occur in other endocrine glands such as the adrenal or thyroid glands, or the intestinal tract.
• The uncontrolled growth of neuroendocrine cells leads to the development of carcinoid tumors. Most carcinoid tumors originate in the small intestine, but carcinoid lung tumors represent about 10% of all carcinoid tumors. Carcinoid lung tumors comprise 1%-6% of all lung tumors.
• There are two types of carcinoid lung tumors: typical and atypical.
  • Typical carcinoid lung tumors are about nine times more common than atypical carcinoid lung tumors. These tumors characteristically grow slowly and only rarely metastasize (spread) beyond the lungs.
  • Atypical carcinoid lung tumors are more aggressive than typical carcinoid lung tumors and are somewhat more likely to metastasize to other organs. They comprise about 10% of all carcinoid lung tumors.
• Some carcinoid tumors produce hormone-like substances that can cause a number of endocrine syndromes. The term carcinoid syndrome has been used to refer to the collection of symptoms produced when a carcinoid tumor secretes hormone-like substances. These syndromes tend to reflect the excessive response of the body to the hormone-like substances produced. However, carcinoid syndrome occurs in only about 2% of people with carcinoid lung tumors.
• About 25% of lung carcinoid tumors are located within the airways and are referred to as bronchial carcinoids. These are not related to smoking or other environmental causes. While anyone can develop a carcinoid tumor of the lung, it may be slightly more common in African-American males.

Unlike most lung cancers, no external environmental toxin (for example, tobacco smoke, air pollution, asbestos, radon) has been identified as a causative agent for the development of carcinoid lung tumors.

About 25% of persons with carcinoid lung tumors are asymptomatic (have no symptoms) at the time of discovery. Most of the time, carcinoid lung tumors are found on a routine chest X-ray done for unrelated medical problems (referred to as an incidental finding).

The severity and range of symptoms depend on the size of the tumor and whether or not it produces hormones.

Persons with carcinoid lung tumors may complain of the following symptoms:

• Cough that does not go away
• Coughing up blood 
• Difficulty in breathing
• Wheezing
• Fever (due to infection in the lung)

Sometimes the health care practitioner considers the possibility of a tumor only after treatment with antibiotics fails to cure a lung infection.

Although uncommon, symptoms of various endocrine syndromes (carcinoid syndrome) can be the initial indicator of carcinoid lung tumors.

The symptoms of carcinoid syndrome include the following:

• Facial flushing (redness and a warm feeling that may last hours to days)
• Sweating
• Diarrhea
• Fast heartbeat
• Weight gain
• Increased facial and body hair
• Increased skin pigmentation

In persons with malignancy (rare), the presence of metastatic disease can produce the following:

• Weight loss
• Weakness
• A general feeling of ill health

Here are common exams and tests for carcinoid lung.

There are no biochemical tests to determine the presence of a carcinoid lung tumor or to diagnose a known lung tumor as a carcinoid lung tumor.

If your healthcare practitioner suspects that a patient has a carcinoid lung tumor, he or she may be advised to undergo some blood and urine tests. Sometimes the hormone-like substances can affect the chemistry of the blood by altering kidney and/or intestinal function and therefore alter the results of certain blood tests. Some tests would detect some of the hormone-like substances or their by-products produced by the carcinoid tumor.

• An abnormal finding on chest X-ray is present in about 75% of patients with a carcinoid lung tumor.
• Findings on X-ray include either the presence of the tumor itself or indirect evidence of its presence (for example,indication of obstruction caused by the tumor).

• Some carcinoid lung tumors that are small or in locations where they are covered by other organs in the chest may not be seen on a chest X-ray. If a patient's health care practitioner is in doubt or there is a vague abnormality on the chest X-ray, the patient may be advised to get aCT scan done.
• CT scna can demonstrate more details about the nodules, masses, or suspicious changes found on chest X-ray.
• A CT scan using intravenous contrast dye also can be useful. Because carcinoid tumors are highly vascular, they may show greater enhancement on CT scan.
• It is useful for characterizing and staging of the tumors.

• MRI generally provides information similar to that of CT scan.
• MRI may be useful for differentiating small tumors from adjacent blood vessels.

• Octreotide scintigraphy or OctreoScan: A small amount of octreotide (a radioactive hormone-like drug) is injected into a vein. The drug is taken up by the cells of the carcinoid tumor. The health care professional uses a special radioactivity-detecting camera to see where the drug accumulates. This exam helps in the diagnosis of a carcinoid lung tumor and determining whether the tumor has spread to other areas of the body.
• Iodine-131 meta-iodo-benzyl guanidine (MIBG) scintigraphy: MIBG is a chemical that is taken up by the cells of the carcinoid tumor. In this exam,radioactive iodine attached to MIBG is injected into the bloodstream. If a carcinoid tumor is present, the scanner will detect the radioactivity and thus help in diagnosing the tumor.

Even if a chest X-ray and/or CT scan shows a tumor, these exams cannot confirm whether the mass is a carcinoid lung tumor, a lung carcinoma, or a localized infection. The only way to verify the diagnosis of a carcinoid tumor is to remove cells from the tumor and examine them under a microscope. This procedure is called biopsy.

A lung biopsy can be done in several ways:

• Bronchoscopy
  • This procedure involves inserting a fiber optic viewing tube called a bronchoscope into the windpipe and the airways of your lungs through the throat.
  • It allows the health care practitioner to visualize the airways of the lungs, and in case a tumor is found, to do a biopsy.
  • In most cases, the physician makes the diagnosis of carcinoid lung tumor based on the findings frombronchoscopy and a combination of radiologic (for example, X-ray, CT scan) studies.
• Transbronchial fine-needle biopsy: If the tumor is small, a fine-needle biopsy of a carcinoid tumor may be performed through the bronchoscope. This procedure is called transbronchial fine-needle biopsy
• Transthoracic needle biopsy: Tumors that are not accessible through bronchoscopy and are located in theperiphery of the lung are accessed using a long needle inserted between the ribs. CT scan images are used to guide the needle into the tumor for taking a biopsy. This procedure is called transthoracic needle biopsy.
• Thoracotomy (surgically opening the chest cavity): In some persons, neither a bronchoscopic biopsy nor a transthoracic needle biopsy can provide enough tissue to identify the type of tumor, and a thoracotomy may be necessary to obtain a biopsy. Usually, the tumor is completely removed during thoracotomy.

What is Staging of carcinoid lung tumor?

Staging is a process of finding out how localized or widespread a tumor is.

• Typical carcinoid tumors, considered the least aggressive form, most commonly are found to be stage I tumors (localized to one area) at the time of diagnosis.
• More than 50% of the less common atypical carcinoid tumors show evidence of further spread to adjacent areas or lymph nodes at the time of diagnosis.
• The outlook for a carcinoid lung tumor depends, to a large extent, on its stage.

There is no medical therapy for the treatment of carcinoid lung tumors.

Surgery is the primary treatment for carcinoid lung tumors.

• Chemotherapy (using medications to kill cancer cells) and radiation therapy (using high-dose X-rays or other high-energy rays to kill cancer cells) have been used in the treatment of carcinoid lung tumors that have spread; however, no success has been achieved.
• A response rate of 30%-35% has been reported using a combination of the drugs 5-fluorouracil (Adrucil) and streptozotocin.
• If the patient is having symptoms associated with carcinoid syndrome (for example, flushing, diarrhea) he or she may be given a drug called octreotide (Sandostatin). Octreotide is not a cure. It is used only when the disease has spread and the patient has symptoms associated with carcinoid syndrome.
• Another drug (MIBG) is taken up by carcinoid cells and damages them. Researchers are studying MIBG to see if it is effective in the treatment of carcinoid lung tumors.
• In some malignant cases, the tumor can spread to the liver. If this is a solitary mass, it may be treated with chemotherapy directed at the hepatic artery feeding the location of the tumor.

The only effective treatment of carcinoid lung tumors is surgical resection of the primary tumor. Most tumors follow a benign course and are amenable to surgery.

Surgical options range from radical resection (the tumor with a good margin of normal tissue is removed) to minimally invasive surgery.

Different surgical options include the following:

• Sleeve resection: A section of the airway containing the tumor is removed.
• Segmental resection: A segment of the lung containing the tumor is removed.
• Wedge resection: Small wedge of the lung containing the tumor is removed.
• Lobectomy: The lobe of the lung containing the tumor is removed.
• Pneumonectomy: Entire lung containing the tumor is removed.
• Endoscopic tumor ablation using laser: This technique involves the removal of the tumor through the bronchoscope, using a laser. It is reserved for treating bronchial obstruction caused by the tumor or reduction of the tumor mass prior to surgical resection. This procedure is rarely curative on its own.

After discharge from the hospital, follow-up is conducted for 8-12 weeks for the following:

• Healing of the wound
• Development of any complications

After surgical resection of the tumor, follow-up for cancer is conducted in a manner similar to that for other lung cancers.

• For the first year after surgery, a clinical examination along with a chest X-ray should be done every 2-3 months.
• If no evidence of recurrence is discovered within one year, follow-up intervals are extended to every 6 months.
• Additional studies, such as CT scans, are only performed if your health care practitioner has suspicion of recurrence of the tumor.

Unlike most lung tumors, carcinoid lung tumors have not been associated with smoking, air pollution, or other chemical exposures. Therefore, there are no known ways to prevent carcinoid lung tumors.

The outlook of carcinoid lung tumors depends on the size of the tumor, the type of tumor (typical or atypical), and whether the tumor has spread to the lymph nodes at the time of diagnosis.

• Because carcinoid lung tumors grow and spread slowly, they often are discovered at an early stage. The outlook for people with early-stage typical carcinoid lung tumors is usually very good. Atypical carcinoid lung tumor is more likely to have spread to nearby tissues or lymph nodes at the time of diagnosis.
• Survival rates are lower for people with atypical carcinoid tumors and carcinoid tumors that have spread to other parts of the body.
• Carcinoid lung tumors generally have a better outlook than other forms of lung cancer. Persons with carcinoid lung tumors have an overall 5-year survival rate of 78%-95% and a 10-year survival rate of 77%-90%.
• Persons with typical carcinoid tumors have been found to have a much better outlook than those with the atypical variety. Atypical carcinoid tumors have been associated with a 5-year survival rate of 40%-60% and a 10-year survival rate of 31%-60%.
• Regardless of the type of carcinoid lung tumor, the presence of lymph node metastases at the time of resection has a significant effect on the outlook.
• The presence of carcinoid syndrome in the absence of spread to the lymph node or other tissues does not seem to affect the outlook adversely.