Prostate Cancer Living with Prostate Cancer

A Side Effect of Cancer Treatment: Diarrhea

Author:

Al Benson III, MD, FACP

Northwestern Memorial Hospital, IL

Medically Reviewed On: August 30, 2002

Millions of Americans are treated for cancer each year, and for many of these people, treatment side effects will pose a significant challenge. Chemotherapy, which targets and kills rapidly-dividing cancer cells, can produce gastrointestinal symptoms, fatigue and hair loss. For some, the side effects of chemotherapy will be debilitating enough to derail the course of treatment.

Below, oncologist Al Benson from Northwestern Memorial Hospital, talks about the dangers of diarrhea associated with chemotherapy, what can be done to treat it and ensure that patients are able to receive the full course of treatments.

How does chemotherapy work, and why does it result in so many side effects?
Most cancer drugs target cells that divide very rapidly, like cancer cells, but we also have normal cells that do this routinely. For example, the cells that line our lips and our mouth, down the throat, the esophagus, the stomach, the small intestine, and the large intestine all grow rapidly. Cells rapidly grow in the bone marrow, and the bone marrow produces important cells that circulate in our bloodstream, such as red blood cells and white blood cells. People lose their hair from chemotherapy because the hair follicles contain cells that divide very rapidly. So the chemotherapy tends to not only hit the cancer cells, but also affect these other types of cells, which can lead to important side effects.

Why does chemotherapy sometimes cause diarrhea?
The treatment kills the rapidly growing cells in the intestinal tract, which results in a very irritated intestine. Normally the intestinal tract is helping us to absorb water and other liquids and foods, but if the lining of the intestine is affected, that process cannot occur, and there is excessive water in the intestinal tract, which leaves the body as very loose stool or diarrhea.

Is this a serious problem?
First, diarrhea can result in socially-related problems. For instance, it can become difficult to leave the house for fear of accidents. It may actually prevent the patient from being able to work and carry out daily activities, including routine care of family members.

People with chemotherapy-induced diarrhea often have significant cramping, which can result in poor eating and drinking habits. If people lose too much fluid and potassium, this can lead, if unchecked, to a life-threatening situation. Diarrhea can also affect the appropriate use of chemotherapy drugs or other medications. It may result in delayed or reduced therapy.

Do patients ever underestimate the dangers of diarrhea?
It's almost impossible for an individual to take enough fluids to make up for the fluid loss that occurs with the diarrhea. That's one of the reasons it's such an important medical problem and why patients end up in the hospital receiving intravenous fluids. If unchecked, severe dehydration, loss of potassium, and in the extreme even death, can occur if this is not appropriately addressed.

What should a cancer patient do if they start experiencing diarrhea?
First, it's critically important to notify the nurse or physician immediately to discuss the significance of the diarrhea. Assessing the severity of the diarrhea, and the cause, needs to occur fairly quickly.

For some people, it's possible to encourage intake of fluids and the use of over-the-counter medications such as loperamide (Imodium). If, however, that does not work quickly, the individual needs to have an evaluation, and what we're looking for is evidence of increasing dehydration, infection or other contributing causes. We need to begin intravenous fluids and to provide replacement of electrolyte loss, such as adding potassium to IV fluids. The dehydration can be severe enough where patients actually need to be in the hospital and stay in the hospital until the diarrhea has resolved. We can also start to consider other medications.

What advice would you give to people who may be suffering with this problem?
If you are experiencing diarrhea, discuss it in detail with your physician or nurse. Don't be embarrassed. It's critical to provide the important details so that your health care provider can figure out why you have the diarrhea and what steps can be taken. For some people there's more than one cause, more than one chemotherapy drug, or more than one reason why it's happening, and sometimes it takes a careful evaluation to locate the cause.

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