* * * * * * * * * *
DIARRHEA AND CANCER
Most people do not associate diarrhea with cancer, the former especially being a common symptom of an infection of the gastrointestinal tract. While considered as an uncommon symptom, diarrhea can occur as a consequence of the cancer itself or as a side effect of the various treatments of this dreaded disease.
Diarrhea As A Direct Consequence of Cancer
According to Dr. Roel Tolentino, surgical oncologist with the St. Luke's Medical Center Cancer Institute, "Most of the time, we see diarrhea after surgery. But with regards to diarrhea during cancer, it's very rare, although we do see it in patients with carcinoid syndrome, pancreatic cancer, gallbladder cancer, and especially those with biliary tract cancer.
"In these patients, there is a disturbance in the enterohepatic circulation caused by an obstruction of the bile ducts by the tumor. If these patients eat fatty foods, these foods will not be absorbed by the small intestines. The fats will act as osmotic particles that will attract water into the lumen of the colon, thereby producing diarrhea. Another mechanism by which diarrhea occurs is that bile also does not get absorbed in the small intestines and when it goes into the colon, it becomes an irritant, producing watery diarrhea."
Diarrhea As A Direct Consequence of Treatment
In patients undergoing treatment for cancer, diarrhea is one of the most common side effects of therapy.
Chemotherapy. "The highest incidence of diarrhea would be found in patients undergoing chemotherapy," explains Dr. Tolentino. "The chemotherapeutic agents affect the rapidly-dividing cells in the body, which include the cells in the gastrointestinal tract. These cells become atrophic and would irritate the lining of the intestines. The thickness of the intestinal lining would be affected and there would be diarrhea because of inflammation."
Diarrhea rates as high as 50 to 80 percent have been documented in chemotherapeutic regimens containing fluoropyrimidines (Ex. 5-fluorouracil) or irinotecan. Reviews of several clinical trials involving a combination of irinotecan, high-dose fluorouracil and leucoverin in colorectal cancer showed early death rates of 2.2 to 4.8 percent as a result of gastrointestinal toxicity."
It is not just these drugs that could cause diarrhea. Says Dr. Tolentino, "Cisplatin can also produce diarrhea, as well as cyclophosphamide, methotrexate and oxaloplatin. Almost all of the major chemotherapeutic drugs can cause diarrhea."
Radiation Therapy. According to Dr. Tolentino, "With radiation therapy, the occurrence of diarrhea would depend upon the dose of radiation and the site in the abdomen that is being irradiated. Usually, a dose of 4,500 to 5,500 rads would produce minimal diarrhea, but as you go higher, the diarrhea becomes a great problem for the patient."
Changes in normal bowel functions can also be expected in radiation therapy to the abdominal, pelvic, lumbar or para-aortic fields. Aside from diarrhea, common side effects of radiation include cramping, gas, bloating and malabsorption.
Surgery. Postsurgical complications of gastrointestinal surgery that may lead to the development of diarrhea include increased transit time, fat malabsorption, gastroparesis, fluid and electrolyte imbalance, and dumping syndrome.
"When we do resection of the small intestine or colon," explains Dr. Tolentino, "the length of the gastrointestinal tract becomes shorter. Because of the faster transit time, food goes down immediately to the distal gastrointestinal tract. Surgery might alter your intestines' ability to absorb nutrients or fat and may result in diarrhea."
What about the current targeted therapies? Can diarrhea also develop? "Targeted therapies are a different kind of therapy. The side effects, including diarrhea, are lesser because these drugs target a specific metabolic pathway. These monoclonal antibodies are different from the usual chemotherapeutic drugs."
Infectious Diarrhea vs. Diarrhea in Cancer
The term diarrhea per se means that there is bowel movement that is more frequent than normal. But how would you differentiate diarrhea as caused by an infectious agent from diarrhea in cancer?
"The clinical presentation is the same," says Dr. Tolentino. "The patients would present with abdominal colic, the same crampy symptoms. The differentiating factor, however, would be fever, which is more common in infectious diarrhea. Fever is not common in patients with cancer. Also, if there is colon or rectal cancer, the first symptom would be constipation, not diarrhea, because the stools cannot pass beyond the obstruction. However, when there is an increase in pressure in the partially obstructed intestinal lumen because of trapped digested food, the stools will just come out, producing bloody, explosive diarrhea."
Treatment and Prevention
According to Dr. Tolentino, the treatment for diarrhea in cancer is the same as the treatment for infectious diarrhea. Oral rehydration preparations are given to prevent dehydration and to correct fluid and electrolyte imbalance. Antidiarrheal drugs such as loperamide and diphenoxylate HCl are not contraindicated.
However, it is the opinion of the good doctor that all cancer patients should seek medical advice for their ailments. "Patients should consult their attending physicians because they are immuno-compromised already. Antibiotics might be needed, and the antibiotic regimen for infectious diarrhea is different from diarrhea in cancer. In infection, we can give metronidazole and chloramphenicol, but in cancer patients, we may give neomycin, which is not absorbed by the intestine. Plus, antidiarrheal agents might not be adequate. It may be necessary to decrease dosage or temporarily stop chemotherapy, allowing a window of healing of about 2 to 3 weeks. After the diarrhea has been resolved, treatment can be continued."
Can a doctor predict which patients will develop diarrhea? "It depends upon the immune system and overall state of health of the patient. If the patient has a good immune system, he/she can resist the side effects of the various therapies. If they are healthy, the side effects, including diarrhea, would be lesser in severity."
Dr. Tolentino says that an ounce of prevention is worth a pound of cure. "Instead of eating three big meals a day, we advise patients with diarrhea to eat six small, frequent meals. Patients should avoid spicy foods and foods with lactose (such as milk and dairy products), and those that are rich in carbohydrates and fats. In those patients with mild diarrhea, they should eat more bulk-forming foods, especially the BRAT (bananas, rice, apples, toast) diet to reduce frequency of stools. Fluid intake should also be increased to at least 3 liters per day. Avoid alcohol and caffeine-containing drinks. From my clinical experience, probiotic foods such as yogurt help modify harmful gut microorganisms that have been implicated in the development of diarrhea."
Diarrhea need not be a life-threatening side effect of a treatment that is meant to save or prolong a life. With the right diet and strict medical supervision, cancer patients will not have diarrhea to add to their physical and emotional distress.
No comments:
Post a Comment