ROCKVILLE, MdResearch on managing cancer pain lags well
behind studies of cancer biology, both in quality and quantity, according to a
new report from the Agency for Healthcare Research and Quality (AHRQ). That
conclusion emerged from a literature review by researchers at the
AHRQ-supported New England Medical Center Evidence-based Practice Center.
In particular, the researchers found a paucity of research on
topics such as quality of life in relation to pain control, drug interactions
during long-term treatment for cancer pain, and the optimal sequence of adding
drugs to improve control of cancer pain.
It also uncovered little work on how best to combine drug with
nondrug therapies, the impact that ethnicity has on cancer pain and patients’
responses to treatment, and analgesia in children with cancer pain.
"While there are many studies being conducted on cancer
and the relief of pain resulting from cancer, this research clearly
demonstrates that there are critical gaps in our knowledge," said AHRQ
director John M. Eisenberg, MD. "An important benefit of evidence-based
research funded by AHRQ is to identify where we need to know more to improve
what we can do for our patients."
Few Patients Enrolled in Studies
The report said that the number of patients enrolled in
methodologically sound studies of cancer pain relief is tiny compared with the
number of patients receiving treatment for the disease, only about 1 in 10,000
Moreover, the number of patients enrolled in pain relief trials
often is too small to allow researchers to draw conclusions. The survey found
that the average number of patients in trials of
primary analgesicsnonsteroidal anti-inflammatory drugs (NSAIDs) and opioidswas
84 (range, 24 to 180) and 68 (range, 10 to 699), respectively. Studies of
bisphophonates enrolled an average of 111 patients (range, 13 to 614).
The literature review identified more than 19,000 studies
related to the management of cancer pain. The researchers concluded that only
24 epidemiologic surveys and 189 randomized controlled trials of treatments
were of high enough quality to be included in the report.
According to AHRQ, analysis of those studies yielded specific
evidence to indicate the following:
Controlled-release morphine and immediate-release
morphine solutions are equally effective at providing pain
Patients receiving rectal morphine have a slightly more
favorable onset and duration of pain relief and experience less nausea than
those treated orally.
Celiac plexus nerve block for pain relief is effective
in pancreatic and other visceral cancers.
Hypnosis can help with procedure-related and
oral-mucositis-related pain in adults and children.