Carcinoid tumors are neuroendocrine tumors that can develop in many organs of the body. The tumors have tendency to grow in the neuroendocrine cells of digestive system such as the stomach, appendix, small and large intestine, rectum and lungs. They can also begin in endocrinal organs such as pancreas, liver, testes, and ovaries. Most carcinoid tumors are slow growing but in some cases they can be highly aggressive and malignant.
Often carcinoid tumors do not produce any signs and symptoms until the cancer is in its late stage because of their slow growth.It is a rare tumor which has estimated prevalence of 2 in 100000 people in United States. Even if the symptoms are present they are often vague and non specific, this causes delay in diagnosis of the disease. The exact cause is not known but old age and family history of endocrinal tumors increase the risk. Treatment includes complete removal of the tumor and medications.
Causes And Risk Factors Of Carcinoid Tumor
The cause of carcinoid tumor is not known. But generally as with any other malignancy, there occurs mutation in the DNA of the cells.This abnormality allows the cells to grow and multiply at a rapid speed whereas the normal cell would die. The collection of abnormal cell will transform into the tumor having its own blood supply. The cells can break and spread to other organs and sites causing metastasis.
Carcinoid tumor is a mixture of neuroendocrine cells. These cells are present throughout the body. The cells partly function as nerve cells and partly as hormone producing endocrine cells. Neuroendocrine cells normally produce hormones such as cortisol, insulin, histamine and serotonin. The cells in stomach, intestine helps in easy motility of the food where as in lungs it takes part in exchange of gases and breathing.Carcinoid tumor in lung does not occur due to smoking.
Although the etiology is not known, several risk factors are suspected. They are:
- Age: The condition is present more in older people then young persons. GI tract carcinoid tumors are diagnosed at an average age between 55 to 65 years. Lung carcinoid tumors are diagnosed at an average age of 45 to 55 years.
- Gender: Carcinoid tumor has tendency to grow in women than in men.
- Race: The tumor is more common in black population as compared to white.
- Family history: Someone having carcinoid tumor in family or tumor of endocrine system.
- Diseases: People having pernicious anemia or those condition in which there is less production of acid have increased risk of developing stomach carcinoid tumor.
Signs And Symptoms Of Carcinoid Tumor
Carcinoid tumor usually do not present with any symptoms in its early stage. The tumor is often found accidentally by the surgeon during an operation performed for some other reason or during X-ray imaging for some other condition. Whenever the symptoms develop they are usually vague.
Most likely symptoms of carcinoid tumor may occur in GI. They usually develop when the tumor is spread to liver. The symptoms develop because of the hormone like substance that the tumor produces. Symptoms appear as follows:
- Red, warm flushed face.
- Nausea and vomiting
- Pain in abdomen due to obstruction of the intestine by the growth.
- Constipation due to obstruction.
- Bleeding from rectum.
- Pain in rectum
- Black tarry stool due to bleeding in the intestine and stomach.
- Increase of hair on face and body.
Symptoms of lung carcinoid tumor:
- Cough that may be dry or with sputum.
- Shortness of breath
- Pneumonia and lung collapse when the tumor obstructs the air passage.
Diagnosis And Treatment Of Carcinoid Tumors
Most carcinoid tumors are non functioning and hence they may not present with any symptoms. This often delays the diagnosis. However, there are useful diagnositic techniques that are useful to identify and localize the tumor. These tests are:
- Blood test: Patient will have high level of hormones in the body circulating in the blood. Since there is production from the tumor.
- Urine analysis: High level of a chemical is detected as a byproduct in urine after the breakdown of hormone produced by carcinoid tumor.
- Endoscope or sigmoidoscopy: The tumor can be detected during endoscopy if it is present in stomach and small intestine. Sigmoidoscopy will detect tumor in colon, rectum.
- Tissue biopsy: Removing a small segment of tissue and sending it for analysis will help to confirm the diagnosis of carcinoid tumor.
The treatment of carcinoid tumor depends on several factors such as location of tumor; whether it has spread to other areas of body, type of hormone secreted and health of the patient.
Treatment may consist of surgery and medication. When carcinoid tumor is detected in its early stage, treatment choice is to remove the tumor completely. However, if the tumor is detected late the surgeon may not be able to remove it completely. In such case, he may remove the tumor as much as possible. If the tumor has spread to other organs such as liver, a partial liver surgery may help to control the symptoms.
Often medications are prescribed that will help to stop production of hormones from the carcinoid growth.