ROCKVILLE, Md—Research 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 patients.
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 analgesics—nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids—was 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:
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Controlled-release morphine(Drug information on morphine) and immediate-release morphine solutions are equally effective at providing pain relief.
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Patients receiving rectal morphine have a slightly more favorable onset and duration of pain relief and experience less nausea than those treated orally.
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Celiac plexus nerve block for pain relief is effective in pancreatic and other visceral cancers.
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Hypnosis can help with procedure-related and oral-mucositis-related pain in adults and children.
