Symptoms and Sources of Carcinoid Tumors

Carcinoid tumors are a form of neuroendocrine tumor. Neuroendocrine tumors are solid malignant tumors that arise from neuroendocrine cells found dispersed throughout the body. Approximately 66 percent of carcinoid tumors originate in the gastrointestinal system.

In women, the primary carcinoid tumor sites are the lungs, stomach, appendix, and cecum of the large intestine. In men the primary carcinoid tumor sites are the thymus, pancreas, duodenum, jejunum and ileum of the small intestine, or rectum.

Carcinoid tumors that originate in the intestines begin deep in the intestinal mucosa lining the inner lumen of the intestines. These solid carcinoid tumors grow slowly and extend into the deeper underlying submucosa and out into the mucosal surface. All carcinoid tumors have the potential to metastasize (send cancerous cells).

Malignant carcinoid tumors can metastasize to other sites in the body. For example, carcinoid tumors in the small intestine most frequently metastasize to the liver.

The early signs and symptoms associated with gastrointestinal carcinoid tumors are usually quite vague and can make a timely diagnosis difficult. The most frequent early signs and symptoms of carcinoid tumors include:

-Abdominal pain

-Rectal bleeding

-Intestinal obstruction

-Constipation

-Abdominal mass

-Diarrhea

-Bleeding from the GI tract

The neuroendocrine composition of these tumors provides the potential for the carcinoid tumor to secrete bioactive substances into the circulation. The secretion of hormones and biopeptides, such as serotonin and histamine, by the malignant carcinoid cells can result in specific symptoms known as Carcinoid Syndrome.

The most frequent symptoms of carcinoid syndrome are include:

-Cutaneous flushing (episodic red flush of the skin)

-Diarrhea

-Carcinoid heart disease (valvular disease)

-Bronchospasms and wheezing

-Arthropathy (joint problems)

-Increased skin pigmentation

-Fibrosis

The incidence of carcinoid tumors is increasing in the United States. Approximately one out of every 100,000 people was estimated to have a carcinoid tumor in 1980, whereas this estimate had increased to five out of every 100,000 people by the year 2000.

Despite the rise in carcinoid tumor rates, there has been little change in the prognosis of patients with carcinoid tumors. Survival rates for individuals with carcinoid tumors are correlated with the extent of disease (localized, regional, distant metastases) and tumor cell differentiation at the time of diagnosis.

Well differentiated or moderately differentiated carcinoid tumors with distant metastases at the time of diagnosis imparts a 5-year survival rate of only 35 percent. In contrast, carcinoid tumors that are poorly differentiated at the time of diagnosis have a dismal 5-year survival rate of only 4 percent.