OHSU Researchers Investigate Fatigue in Cancer Patients

07-07-2005   Portland, Ore.

Oregon Health & Science University researchers led by Lisa Wood, Ph.D., R.N., want to figure out why cancer patients experience debilitating fatigue. Fatigue often is a side effect of chemotherapy, a symptom of cancer and a result of other treatment related problems like anemia. Wood points out that most of the research so far has focused on anemia, but cancer patients who are not anemic experience severe fatigue. In some cases the fatigue is so severe that patients are forced to stop their cancer treatment. Fatigue also can persist for years after treatment has ended, negatively affecting the patient's quality of life.

"The care and health of cancer patients can be improved by understanding how chemotherapy and/or cancer induces fatigue," said Wood, an Oregon Opportunity funded assistant professor in the OHSU School of Nursing and a member of the OHSU Cancer Institute.

A $600,000 grant from the American Cancer Society funds this research.

Because many cancer-related symptoms such as pain, anemia, depression, loss of appetite, weight loss and sleep disturbance could contribute to the fatigue experienced by cancer patients, researchers believe that to effectively address treatment-related fatigue, they must first understand the mechanisms underlying these other symptoms.

Symptoms experienced by cancer patients are similar to those associated with "sickness behavior," which occurs when the immune system responds to potentially harmful stimuli like bacteria or viruses by increasing production of blood proteins called pro-inflammatory cytokines. Because of this similarity, Wood decided to look at the levels of pro-inflammatory cytokines in mice that get chemotherapy but without cancer and those with cancer but no chemotherapy. To do this, Wood has developed an innovative mouse model to evaluate the relationship between cancer, chemotherapy, levels of pro-inflammatory cytokines and treatment-related symptoms. 

Because mice can't talk about their symptoms, behavioral tests are used. Depressed mice float rather than swim when placed in water, tired mice run less on their wheels, and a mouse with no appetite stops eating.

Preliminary findings support Wood's hypothesis that cancer-related symptoms are caused by pro-inflammatory cytokines that are produced in response to the chemotherapy or the cancer.

"Our long-range goal is to develop targeted therapies to effectively treat and manage cancer-related symptoms and cancer-related fatigue. If we find that pro-inflammatory cytokines are involved, then drugs that decrease their production could be used to treat these symptoms," Wood said.

"Dr. Wood's project is a perfect example of the approach encouraged by the OHSU Cancer Institute for all of our cancer researchers," said Grover Bagby Jr., M.D., director of OHSU Cancer Institute. "We believe that by understanding the molecular basis of cancer and the symptoms caused by cancer and its treatment we can substantially improve the quality of life for cancer patients."