Cancer Patients' Loss of Taste and Smell Can Compromise Treatment Success
SARASOTA, FL -- Cancer patients who experience taste and smell loss because of the disease and its treatments are at high risk for weight loss and nutritional deficits that can compromise their overall treatment success, according to a small study of 33 lung cancer patients at Duke University Medical Center.
While not all cancer patients lose weight with the disease, those who do so tend to have a poorer prognosis for treatment outcome and long-term survival, said Jennifer Garst, M.D., a study author and assistant professor of oncology at the Duke Comprehensive Cancer Center.
Thus, finding ways to prevent weight loss and nutritional deficits is critical to helping patients respond more effectively to treatments and even live longer, she said. The scientists are now continuing the study to explore the whether the addition of flavor-enhancing powders, derived from actual foods such as cheese, bacon, garlic and fruits, can improve the patients' appetite.
Results of the study are being presented at the annual Association of Chemoreception Sciences by the study's co-author, Susan Schiffman, Ph.D., on April 25. Jennifer Zervakis, Ph.D. and Lara Campagna are also authors of the study, funded by the National Institute on Aging.
"Weight loss has long been a hallmark of cancer, but it has been considered an inevitable byproduct of the disease process and chemotherapy drugs, rather than as a treatable symptom that can affect outcomes," said Schiffman, professor of medical psychology at Duke. "If we can show that taste and smell deficits are responsible for the weight loss in a specific population of patients, then we can intervene and potentially improve patient outcomes."
More than just a nuisance, taste and smell deficits have been associated with reduced levels of key immune system cells, such as T-cells and B-cells, in elderly patients tested at Duke, said Schiffman.
Even among patients who are eating the same volume of calories, those with taste and smell distortions may avoid foods with high nutritional value, such as fresh fruits and vegetables. Eliminating such nutritious foods can further depress immune function, said Schiffman.
The causes of appetite and taste loss are many, said Garst. Chemotherapy drugs are known to alter taste and smell by blunting the normal turnover rate of taste and smell receptors on the tongue and in the nasal passages. Radiation treatments can also damage taste and smell receptors, giving food a metallic flavor. Tumors themselves also secrete a protein that suppresses appetite in some patients.
While certain drugs can improve appetite and taste sensation, some of them – like steroids – carry their own risks and unwanted side effects. The Duke study was designed to measure the impact of taste and smell deficits on patients, and then to investigate a non-drug alternative for making food more appealing.
In the study of 33 lung cancer patients undergoing chemotherapy, the Duke researchers assessed the patients' own perceptions of their taste and smell deficits, then scored their ability to detect and recognize odors and flavors presented to them in a laboratory. Patients who reported the lowest degree of taste and smell ability, and who scored the lowest on the psychophysical measurements, also experienced the most weight loss, body-mass loss and nutritional deficits.
Half the patients were then given powdered flavor enhancers – extracts of natural foods combined with amino acids -- that strengthen the smell and taste of foods. The other half of patients received no enhancers. All patients received nutritional advice and worksheets explaining what foods help alleviate dry mouth, constipation, diarrhea and other side effects of treatments.
Zervakis said their hypothesis is that patients who receive the flavor enhancers will lose less weight and will show higher immune status at their eight-month checkup than patients who do not receive the flavor enhancers.
In previous studies conducted by Schiffman, elderly patients who ate foods enhanced with powdered flavors like beef, bacon and cheese showed significantly higher levels of B-cells and T-cells than when they ate the same foods without enhancers.
If the treatment proves successful in cancer patients, it will provide an important tool in helping to combat the weight and body-mass loss patients often experience, said Garst.
"As oncologists, we can become so focused on the medical treatments of the disease that we overlook the importance of factors like weight loss and nutritional status. Both of these factors have a huge impact on quality of life and long-term survival," said Garst. "The patients themselves are very excited about this study because it improves the pleasure they derive from food and it can positively impact performance status."