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NEW YORK (Reuters Health) - Despite encouraging results in the past, melatonin pills did nothing to help advanced cancer patients eat more or stave off weight loss in a new clinical trial.
"We had great enthusiasm for it also based on these other trials, and were quite disappointed when it didn't work," lead author Dr. Egidio Del Fabbro told Reuters Health.
Some previous studies had suggested the hormone, which is involved in appetite and metabolism as well as sleep cycles in healthy adults, may increase appetite in cancer patients when taken in supplement form. But those studies did not include a group of patients given dummy pills for comparison.
"The reason for these other trials being positive was the placebo effect," said Del Fabbro, who studies rapid loss of muscle mass in cancer patients - a condition known as cachexia - at the University of Texas MD Anderson Cancer Center in Houston.
Del Fabbro and his colleagues divided 70 patients with advanced lung or gastrointestinal cancer, poor appetite and recent unintentional weight loss into two groups. One group took 20 milligrams of melatonin every night for 28 days, and the other group took a placebo for the same period.
At the end of four weeks, the melatonin and placebo groups had essentially the same appetite, weight changes, pain levels and quality of life scores, Del Fabbro's team reports in the Journal of Clinical Oncology.
For example, one representative patient in the melatonin group with a starting weight of 147 pounds lost almost two pounds during the study period, and one in the placebo group who started at 145 pounds also lost two pounds.
In late stage cancer, the body aggressively breaks down its own muscle mass, and patients have decreased appetite, nausea and reduced ability to absorb the nutrients they do eat.
"It's vital, it's probably the most under-recognized condition in advanced cancer," and often bothers families the most, Del Fabbro said. "Families feel (the patient) should just eat more, they should try harder," he said.
Treatment options are currently very limited, said Vickie Baracos, a professor of palliative care medicine who wrote an editorial accompanying the study.
High dose steroids can stimulate appetite, but extended use also causes muscle wasting and diabetes-like insulin resistance, so doctors often avoid using them, said Baracos, of the University of Alberta in Edmonton, Canada.
Melatonin, which is produced naturally in the body and available in supplements, does affect appetite, metabolism and control of body weight in healthy adults, according to Baracos. But that doesn't mean it will work for people with cancer, she said.
Melatonin is available in pill form in the U.S. without a prescription. A bottle of 5- or 10-milligram capsules costs about $10 at a drugstore.
Many cancer patients turn to potential remedies found on the Internet that have not been studied, Baracos said. She has known late-stage cancer patients to take up plant extracts, juices from tropical fruits, horse milk, and diets consisting mostly of cottage cheese.
"It's important to vet these other options, the trouble is getting federal funding," said Del Fabbro, whose department financed the melatonin study without outside support.
The hormone didn't cause any negative side effects, even at the high dose of 20 milligrams per day, he said, and it could be tried in another trial with cancer patients earlier in the progression of the disease to see if the results are different.
If advanced cancer patients still want to take melatonin, Baracos said, this trial indicates at least that it's unlikely to hurt them.
"Now a doctor has some evidence of good quality to stand on: it doesn't work, but it also doesn't do any harm," she said.
SOURCE: bit.ly/WtQ0en Journal of Clinical Oncology, online February 25, 2013.