Course of Chemotherapy

Most people know that chemotherapy for cancer can cause hair loss and nausea, but there are other chemotherapy-induced side effects, some with potentially serious consequences. Severe diarrhea associated with certain chemotherapy regimens can throw the course of cancer therapy off track. Doctors are sometimes forced to adjust the scheduling and dosages of treatments, or in some cases, abandon treatment altogether, lessening the chances of an improved disease outcome.

Chemotherapy-induced diarrhea is distinct from more common forms of this gastrointestinal condition such as stomach bugs, so treatment for it must address its specific underlying causes. Below, Dr. Stephen Rosenoff, of Oncology and Hematology Associates of Southwest Virginia, explains what causes chemotherapy-induced diarrhea and what available treatments can help ensure people with cancer stick to their chemotherapy regimes—and maintain a high quality of life.

Is diarrhea something that is always a problem with chemotherapy?
It's not universally a problem. All of the side effects with chemotherapy are specific to the drugs and the schedule used. With some schedules, nausea and vomiting will be the major problems, and for other treatments, diarrhea will be the major problem.

With the drugs that we use, for instance, for the adjuvant treatment of colorectal cancer—by adjuvant I mean treatment offered after surgery—the major problem is diarrhea. With this particular treatment, nausea and vomiting and hair loss are rare, but diarrhea can be a big problem that will influence treatment compliance and outcome success. It'll become a major patient focus and problem, and it can not only influence the course of therapy, but lead a significant number of patients to refuse to continue treatment because of the diarrhea.

Why can chemotherapy cause diarrhea?
The diarrhea that is associated with chemotherapy is different than diarrhea that's associated with viral illnesses, food poisoning, colitis or other conditions.

In chemotherapy-induced diarrhea, there are two problems. One is that there's an increase in the secretions because of the effects of the chemotherapy on the gut lining. Secondly, you have damage to the gut lining, so the gut can't absorb the fluids that are presented even normally.

Most of these diarrheas are related to irritation of the bowel and rapid transit time. Rather than having enough time for fluids to be absorbed in the gut, things move through too quickly, and therefore the stool is more loose or watery.

Chemo-induced diarrhea is a very different problem and requires a unique approach. Therapies that we would normally use, such as the conventional over-the-counter diarrhea drugs, can be effective in people with very minimal diarrhea associated with chemotherapy. But it will prove ineffective in the more severe diarrhea associated, for instance, with drugs that are used in adjuvant therapy of colon cancer.

How can diarrhea affect chemotherapy plans?
Studies have shown that approximately 15 percent of patients who experienced chemotherapy and diarrhea refused further treatment. These patients stopped therapy not only because of the bothersome nature of the diarrhea, but because of cramping and abdominal pain, fear, discomfort and a general decrease in quality of life. People said, "This just isn't worth it. I'm just not going to continue."

The second big problem is that it pushes doctors to reduce the doses of chemotherapy. The dose may be lowered to a point that can be tolerated by the patient with conventional antidiarrheal treatments, but the dose can then be too low to really affect the cancer in a meaningful manner.

Another problem, other than dose adjustment, is schedule adjustment. It causes people to have long breaks between treatments, which could also negatively affect treatment outcomes.

How do you treat chemotherapy-induced diarrhea?
The severity of the diarrhea is extremely important, as it directly affects the type of treatment that a physician would want to initiate. If the diarrhea is very mild—a few loose bowel movements a day, no severe cramping pain, doesn't require the patient to need intravenous fluids to maintain their fluid intake—then conventional antidiarrheal treatments such as Imodium can work in the majority of cases.

With severe diarrhea, people are having six to eight bowel movements a day, cramping and abdominal pain, and often require intravenous fluids to maintain the level of hydration. In the majority of these cases, diarrhea will not be successfully treated with any of the conventional treatments.

In these patients, I've found it very useful to initiate treatment with a hormone therapy that mimics the action of a hormone made in the body called somatostatin, which plays a role in regulating secretions in the gut. In the overwhelming majority of cases, this can bring fairly prompt resolution to diarrhea within two to three days. And this is given as a shot, just like insulin. We can also instruct the patient, a family member or a friend to give these injections at home. At the same time, I start therapy with a long-acting compound that is an intramuscular injection that then is given once every four weeks during the treatment.

Ninety-plus percent of the patients that I treat in this manner, regardless of severity of the initial chemotherapy-induced diarrhea, can continue their treatment at full dose and on schedule. They do not need more than the occasional Imodium and can have better quality of life.

How does hormonal therapy treat chemotherapy-induced diarrhea?
The conventional antidiarrheal therapies work predominantly by slowing the gut. Any benefit you get by increasing the absorption of excess fluids is only by virtue of slowing the gut, and they primarily act by slowing the large bowel and not the small bowel. The large bowel is only responsible for about a quarter of the fluids absorbed, so with chemo-induced diarrhea you really need to slow the small bowel; hormonal therapy can slow the small bowel. More importantly, it interferes with the excess secretion of fluids, which is one of the major problems in chemotherapy-induced diarrhea. So it has this double action of being antisecretory as well as slowing the gut, and also enhances fluid absorption.

Are there any side effects with hormonal therapy?
Like with any drug, there are reported side effects, but they are extremely few and far between. Surprisingly, diarrhea can occur at the initiation of therapy and tends to result from the inhibition of the release of pancreatic enzymes. This can cause a temporary fatty food intolerance. Constipation can occur, but that's very rare. And the potential always exists for an allergic side effect, but that is also rare.

Copyright HLTHO - Healthology
Contact Us