Study: Low-Dose Morphine Better Than Weak Opioids for Moderate Cancer Pain

Study: Low-Dose Morphine Better Than Weak Opioids for Moderate Cancer Pain

People who experience moderate cancer pain gain significantly greater pain relief when treated with low-dose morphine compared to weak opioids, a study published in the Journal of Clinical Oncology this month concludes.

The purpose of the study was to tease out whether the World Health Organization (WHO) guidelines on managing cancer pain – a three-step analgesic ladder – can be more definitive in guiding the treatment of moderate cancer pain.  There are no conclusive data on whether moderate cancer pain should be treated with a step II weak opioid or a step III strong opioid.

In a multicenter, open-label, randomized controlled trial, 240 adults with moderate cancer pain received either a step II weak opioid, like codeine phosphate, or low-dose step III strong opioid, like morphine, for 28 days. They rated their pain intensity on a numerical pain scale.

The primary outcome was the number of study participants who experienced a 20% reduction in pain intensity.

Slightly more than 88% of those taking low-dose morphine achieved a 20% reduction in pain intensity, while just under 58% of those taking weak opioids achieved that same outcome.

The Italian researchers found that the participants on the low-dose morphine group experienced a 20% pain reduction as early as the first week of the 28 day treatment.

“Clinically meaningful (≥ 30%) and highly meaningful (≥ 50%) pain reduction from baseline was significantly higher in the low-dose morphine group (P < .001),” the authors wrote.

Many in the group taking weak opioids had to change to low-dose morphine because they were not achieving adequate pain relief.

The authors did note that the overall condition of the participants in the low-dose morphine group “was better” as defined by the Edmonton Symptom Assessment System.  They also noted that adverse effects were about the same in both groups.

These findings from the study, Randomized Trial of Low-Dose Morphine Versus Weak Opioids in Moderate Cancer Pain, may help oncologists and pain management specialist re-assess the Pain Ladder when managing moderate cancer pain by skipping step II and starting treatment with low dose morphine.

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Authored by: Staff

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Jeremy Goodwin

The up to 40x difference in dose required between individuals in pain is multi-factorial. The genetics of receptor morphology and responsiveness to specific agents varies as does the rate of metabolism of pain relieving compounds. Codeine is metabolized in part to low dose morphine, however 8-15% of Caucasions lack the enzyme necessary for such conversion. Some metabolic pathways are interfered with by concurrent use of other agents.

While I would not, in general, choose codeine as a pain reliever over morphine, I am not sure what this study really ‘proves’. How was the pain rated and by which validated models? How were responses standardized as much as possible? The 30% and 50% cut offs for significance of pain relief is pretty arbitrary and not as meaningful as might be inferred by the reader or implied by the researchers.

Was mood, sleep and level of anxiety controlled for? Frankly, I am surprised that this study was reported without such points having been discussed, let alone others more directly involving the pathology itself.

Mark Ibsen

Using opiates without the DNA test is like using antibiotics without
Culture and sensitivity testing.
Lots of hit and miss.
This is where you find chronic pain patients expressing a preference for certain opiates, and of course the ridiculous response from healthcare providers that they are drug seekers.
Of course they are. We physicians provide either drugs or surgery. There are a lot of patients who are “surgery seekers”
No worries we blame them too.

Mark Ibsen

Recall that the cyp450 system metabolizes opiates differently in different people.
Wide variations.
Thus genetic DNA test is now widely available, and it’s cost is rapidly decreasing.

Dorian W

I would think that since i have worked with several cancer patients that it depends on the person. every patient is different. with some they may need a very strong dose even if the cancer is exactly the same. every person i have helped with or without cancer have needed pain medication and they all react differently.