Cancers Causing Diarrhea

The following cancers can (rarely) cause diarrhea:

  • Spread of any tumor (metastasis) into any abdominal organ
  • Hormone-producing tumors causing carcinoid syndrome (read below) or Zollinger-Ellison syndrome(pancreatic or duodenal cancer secreting large amounts of gastrin resulting in peptic ulcers, nausea, GERD and diarrhea)
  • Colorectal cancer
  • Intestinal lymphoma
  • Medullar cancer of the thyroid
  • Pancreatic cancer
  • Cancer of the gallbladder and bile duct
  • Hepatocellular cancer

Abdominal cancers often do not cause any symptoms until advanced stage. Even colorectal cancer more often causes constipation than diarrhea. Other cancers causing diarrhea by secreting bowel stimulating substances are rare.

Morphine narcotics, like codein, and anti-diarrheal drugs, like loperamide (Imodium), may reduce 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. 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, 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 into 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 of carcinoid 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).


Article reviewed by Dr. Greg. Last updated on May 24, 2010