What causes diarrhea in people with cancer?

Everyone gets diarrhea now and then. If you have cancer, the things that normally cause diarrhea can still affect you. But there are additional causes of diarrhea in people with cancer, such as:

• Cancer treatment. Some cancer treatments can cause diarrhea, including chemotherapy, radiation, surgery (if certain parts of the intestine need to be removed) and bone marrow transplants.
• Infections. Cancer treatment can make you more susceptible to various infections, which can cause diarrhea. Antibiotics used to treat some infections also can cause diarrhea.
• Cancer itself. Certain cancers can cause diarrhea, including hormone-producing (neuroendocrine) tumors, such as carcinoid syndrome and Zollinger-Ellison syndrome; colon cancer; lymphoma; medullary carcinoma of the thyroid gland; and pancreatic cancer.

The duration and severity of your diarrhea depend on what's causing your signs and symptoms. Talk to your doctor about what you can expect and how long your diarrhea may last.