It's not clear how much of that benefit could have been a result of patients' expectations that acupuncture would help them or the effect of a therapeutic relationship with their acupuncturist - rather than the actual needles - researchers said.
"These are patients for whom no other treatment has been helpful, and they feel better and their life has been improved as a result of this intervention," oncologist Dr. Richard Simcock, from the Sussex Cancer Centre in Brighton, told Reuters Health.
Dry mouth is a common side effect of radiation treatment for head and neck cancers, but the only prescription drug used to treat it - known as Salagen (pilocarpine) - comes with side effects. Other options, like special toothpastes and mouthwashes, don't always offer relief.
Acupuncturists have been convinced their therapy could help these patients for years. But there hasn't been much evidence for or against it, and head and neck cancer patients typically don't seek out alternative medicine, according to Simcock.
His team's study included 144 patients from seven UK cancer centers who had chronic dry mouth after radiation for head or neck cancer. They were all more than a year and a half out from radiation therapy.
The researchers sent participants to two hour-long educational sessions on oral care or eight weekly 20-minute sessions of group acupuncture targeting traditional points in the head and fingers believed to influence the salivary glands.
After the first round of treatment ended, patients switched assignments.
By the end of their acupuncture sessions, participants were between 1.65 and 2.08 times more likely to report improvements in five of six dry mouth symptoms, including having to wake up at night to drink water, than after they'd only learned about oral care.
Still, of patients with severe dry mouth at the start of the study, only about one-quarter reported an improvement.
WHAT'S BEHIND THE EFFECT?
The findings are partly limited by the study design, researchers said. In an ideal trial, participants wouldn't know if they were getting real acupuncture or a fake treatment without any expected benefit.
Because of the difficulty of finding a "control" group to compare to acupuncture treatment, it's hard to know how much of the benefit was really due to the effects of the needles themselves, rather than patient expectations.
Participants' saliva production was no different after acupuncture than after the oral care sessions, Simcock and his colleagues reported Wednesday in the Annals of Oncology.
The researcher said future studies should look into how long the effects of acupuncture last, as well as what may explain its benefit.
Some theories suggest acupuncture might directly stimulate the salivary glands, he said, or increase brain activity in ways that affect how patients perceive their dry mouth symptoms.
And even if the placebo effect is largely driving the results, it's not a reason to dismiss acupuncture, some researchers say.
"Even though we know a portion of acupuncture (benefit) is due to placebo, the patients reported improvements, and at the end of the day the objective... is to improve how people feel," Lorenzo Cohen, a cancer researcher from the University of Texas MD Anderson Cancer Center in Houston, who wasn't involved in the new study, told Reuters Health.
Simcock said because acupuncture was done in a group setting in the new study, each practitioner could treat up to seven patients in an hour. With compensation of about $50 to $60 per hour, that makes the treatment cost-effective when it's done in a place with high demand, he added.
"I think it is a treatment that can and should be offered within cancer centers," Simcock said.
Dr. Lawrence Berk, head of radiation oncology at the University of South Florida in Tampa, called the results "kind of a mixed picture."
"The advantage of something like this is that it's very non-invasive," Berk, who also didn't participate in the new research, told Reuters Health. "If you didn't get the benefit, there's no harm done outside of cost."
Cohen agreed that as long as it's delivered by a qualified practitioner, acupuncture is very safe.
Soreness can be a side effect, and rare complications of acupuncture include infections and organ damage.
SOURCE: http://bit.ly/wctYGR Annals of Oncology, online October 24, 2012.