From Medscape Medical News > Oncology
Roxanne Nelson
February 25, 2011 — The active ingredient in cannabis appears to help stimulate the appetite of patients with advanced cancer, according to the results of a pilot study. Canadian researchers also found that delta-9-tetrahydrocannabinol (THC) can improve the sense of taste in this population.
The findings come from a randomized study of nearly 50 patients published online February 22 in the Annals of Oncology.
In this study, the authors used a synthetic form of delta-9-THC, which is marketed as dronabinol (Marinol, Solvay). Dronabinol was first licensed and approved in 1986 for the treatment of nausea and vomiting associated with chemotherapy; the indication was expanded in 1992 for the treatment of anorexia associated with weight loss in patients with AIDS.
In the THC (dronabinol) group, 64% experienced an increase in appetite and 27% experienced no change. In the placebo group, 50% experienced a decrease in appetite and 20% experienced no change.
In the THC goup, 73% reported "an increased overall appreciation of food," compared with 30% in the placebo group. Those in the THC group were also more likely to say that it "made food taste better" than those in the placebo group (P = .04).
In addition, patients who received THC consumed more protein, even though total caloric intake was similar for the 2 study groups (P = .008). Participants in the THC group also reported improvements in their quality of sleep (P = .025) and relaxation (P = .045).
"Based on the results of our study, doctors could consider THC to improve both appetite and food enjoyment for advanced cancer patients," lead author Wendy Wismer, PhD, told Medscape Medical News.
"When approved for use in the cancer setting, it could be integrated into therapy. When researching the topic, we did not find anything to suggest that long-term use should not be considered," added Dr. Wismer, associate professor at the University of Alberta in Edmonton, Canada.
Cannabis Known to Stimulate Appetite
Dr. Donald Abrams
However, in an independent comment, Donald I. Abrams, MD, professor of clinical medicine at the University of California, San Francisco, pointed out that these data really aren't all that new.
"I don't think there's anything startling about the fact that cannabis or cannabinoids increases the appetite," he said in an interview. "That's been well known for years."
In this study, Dr. Abrams noted, the authors suggest that THC improved the sensory aspects of food, such as taste and smell. "Other research that we're more familiar with suggests that cannabinoid receptors in the brain that are involved with the reward aspect of eating are stimulated when they complex with either the plant cannabinoids or endocannabinoids," he said.
"We've always known that cannabinoids are involved in the regulation of appetite, the interesting point in this study is that it enhanced the sensory aspect of eating via taste and smell," added Dr. Abrams, who is also director of the Integrative Oncology Research Program at the Osher Center for Integrative Medicine.
One explanation for the findings might be that the authors only looked at delta-9-THC, which is just 1 of 400 components of cannabis. "There are probably about 70 other cannabinoids in the plant, so to show that this single most psychoactive component led to these findings might be noteworthy," Dr. Abrams explained.
Grow Your Own?
Cannabis in its natural form is still considered illegal by the US federal government, although several states — including California — have passed laws that allow it for medicinal use.
However, Dr. Abrams noted that dronabinol is unlikely to be approved for the palliation of chemosensory alterations or to improve food enjoyment among cancer patients. "I don't think that any insurance companies are going to pay for this indication — to improve chemosensory perception. It is very expensive to use [dronabinol]," he said.
"I think it's cheaper to grow your own; then you get a benefit from the many other compounds in the cannabis," Dr. Abrams added.
In addition, he noted that because it is ingested orally, dronabinol has a slower onset of action and lower rate of absorption. In comparison, smoked or inhaled cannabis has a rapid onset of action — peak plasma levels are reached very quickly — and patients are better able to control dosing.
Previous studies have shown that both smoked cannabis and synthetic THC can offer medical benefits. For example, smoking cannabis appears to reduce posttraumatic or postsurgical neuropathic pain and improve sleep, as previously reported by Medscape Medical News.
It also appears to be effective for the treatment of HIV-related sensory neuropathy, and for delayed and acute chemotherapy-induced nausea and vomiting.
Improved Taste and Smell
The current study was conducted in adult patients with any advanced cancer (defined as locally recurrent, locally advanced, or metastatic) of any site except the brain. Patients were randomized to receive either THC 2.5 mg (n = 24) or oral placebo capsules (n = 22) twice daily for 18 days. The authors explain that because this was an exploratory study, the nature of treatment effects and potential effects were unknown. For that reason, 10 participants from each group were assessed at the end of the 18-day study period. Overall, 21 patients completed the trial.
At baseline and following treatment, all patients were interviewed and completed a panel of patient-reported outcomes: the Taste and Smell Survey, a 3-day food record, appetite and macronutrient preference assessments, and a quality-of-life questionnaire.
Half of the patients in the THC group who reported food odors to be unpleasant at baseline did not find them offensive after treatment (P = .083), and nearly three quarters reported a "renewed ability" to discriminate tastes, flavors, and food odors. In comparison, 80% of those in the placebo group found that their taste and smell function had not changed or had worsened.
Quality-of-life and nausea scores were similar for both groups. Overall, THC was well tolerated and there were no differences in adverse events between the 2 groups during the trial period or within the 30-day follow-up period.
"Our findings are important, as there is no accepted treatment for chemosensory alterations experienced by cancer patients," write the authors. They suggest that THC treatment might have multiple clinical benefits for cancer patients, "beyond its indication as a treatment for nausea and its effects on appetite."
This work was supported by the Canadian Institutes of Health Research, the Alberta Cancer Board, the Alberta Heritage Foundation for Medical Research, and the Natural Sciences and Engineering Research Council of Canada.
Ann Oncol. Published online February 22, 2011. Abstract
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