New study questions common belief that opioids are the most effective painkillers

A University of Sydney-led study has challenged the common belief that opioids are the most effective cancer painkillers, revealing significant gaps in the evidence and suggesting NSAIDs as a potential alternative. This study advocates for more informed choices in cancer pain treatment, emphasizing patient empowerment and consideration of non-opioid options.

A new review challenges our understanding of the role of opioids in cancer pain. When researchers looked at data on opioids for cancer-related pain, they found a large evidence gap about how effective these drugs actually are in relieving cancer pain. This review challenges the widely accepted view that opioids are the most effective analgesics.

The study, led by the University of Sydney, highlights that there is no "one-size-fits-all" approach to cancer pain treatment and urges medical professionals and patients to carefully weigh the evidence when deciding on appropriate pain treatment options.

Reevaluating Opioid Analgesics

Opioid analgesics are the most commonly used medications to treat cancer pain. Many international guidelines, including the World Health Organization, recommend the use of opioids to control both background cancer pain (persistent pain) and breakthrough cancer pain (transient episodes of pain in addition to background pain).

However, the study found few trials comparing commonly used opioids such as morphine, oxycodone and methadone with placebo.

The study found no convincing evidence that morphine is better or safer than other opioids in the treatment of cancer pain in settings other than hospice.

Although doctors generally consider morphine the "gold standard therapy" for cancer treatment, many international clinical guidelines also recommend its use for the treatment of moderate to severe cancer pain because of its low cost and easy availability.

Other pain treatment options

The review also found that nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin and diclofenac, may be at least as effective as some opioids in treating background cancer pain.

"The lack of evidence comparing opioids for the treatment of cancer pain with placebo may reflect the ethical and logistical challenges of conducting such trials," said lead researcher Dr Christina Abdel Shaheed, from the University of Sydney's School of Public Health, School of Medicine and Health and Sydney Musculoskeletal Health Centre. "However, these trials are necessary to guide clinical decision-making."

"In practice, opioids are indispensable for refractory pain and suffering at the end of life. It is worth emphasizing that non-opioid drugs, especially NSAIDs, are surprisingly effective in some cancer pain and can avoid dependence and the problem of opioid analgesia waning over time," said co-author,said Professor Jane Ballantyne of the University of Washington School of Medicine.

Co-author, UKProfessor Martin Underwood from the University of Warwick said: "People with background cancer pain may have a better overall experience of life if there is less focus on using opioids to reduce pain levels."

"We hope these findings will help guide physicians and patients in their choices among different opioids to treat cancer pain, and allow patients to consider alternatives if they cannot tolerate opioids or choose not to take them," said the study's senior author, Dr. Mark Sidhom of the Cancer Treatment Center at Liverpool Hospital in Australia.

Main findings

The study reviewed data from more than 150 published clinical trials.