Cancers Causing Diarrhea

The following cancers can (rarely) cause diarrhea:

  • Spread of any tumor (metastasis) into abdominal organs
  • Hormone-producing tumors causing carcinoid syndrome (read below) and Zollinger-Ellison syndrome
  • Colorectal cancer
  • Lymphoma
  • Medullar cancer of the thyroid
  • Pancreatic cancer
  • Cancer of the gallbladder and biliary duct
  • Hepatocellular cancer

Abdominal cancers often don’t cause any symptoms until advanced stage. Even colorectal cancer rarely causes diarrhea. Other cancers (like carcinoid or medullar cancer of the thyroid) causing diarrhea by secreting bowel stimulating substances are rare.

Morphine narcotics like codein and anti-diarrheal drugs like Loperamide may reduce frequency of stools in diarrhea caused by cancer.

Carcinoid Tumor and Carcionid Syndrome

Carcinoids are rare, slowly growing tumors (in midway between benign and malign ones), which mainly occur in people after 5o, usually affecting their small intestine, appendix, colon, lungs, stomach, pancreas or liver (21). Among other substances, they secrete serotonin, which may cause dilation of arteries and spasm of the bronchi, and is responsible for symptoms of carcinoid syndrome: flushing (lasting from 30 seconds to 30 minutes), heart palpitations, low blood pressure, abdominal cramping or diarrhea, spider-like small veins on the skin, limbs swelling, wheezing (in bronchial carcinoid) or cyanosis (bluish skin spots after the flushing episode).

Carcinoid crisis, a severe epizode of symptoms that may (rarely) be fatal, can appear spontaneously or it can be evoked by stress, meal or alcohol. Carcinoid crisis is usually due to intestinal carcinoid tomor that has spread to the liver, from where serotonin can easily enter the bloodstream.

Diarrhea in carcinoid syndrome appears in minutes after eating, often together with flushing of face and upper chest.

Diagnosis is by finding 5-HIAA, a breakdown product of serotonin in the urine, and by elevated levels of blood serotonine. OctreoScan, CT and MRI are used to find a location of carcinoid tumor.

In children, carcinoid usually occurs in appendix, so appendix removal cures the disease in most cases. Surgery is also successful in adults when tumor can be removed completely. Chemotherapy helps to one third of patients. Drugs, like Sandostatin (octreoide) and interferon, may stop the growth of the tumor. In liver metastases, embolization of the hepatic artery may be performed. Carcinoid tumor may cause intestinal bleeding or intestinal obstruction. Prognosis is better when there are less symptoms and when tumor can be completely removed. 

Low fat, high protein diet can help in diarrhea. Multivitamin supplements, especially niacin may help in skin changes (pellagra).