Morphine prescribed to relieve pain from cancer may actually increase tumour growth by boosting the formation blood vessels that deliver oxygen and nutrients, according to US research.
Dr Patrick Singleton at Chicago University has told the American Association for Cancer Research that in lab tests, morphine also seems to make it easier for cancers to spread.
However, this can be overcome by the drug methylnaltrexone (MNTX), which was developed in the 1980s to prevent morphine-related constipation, but only recently approved in the US.
It appears to work without interfering with the pain-relieving properties of the opiate, and in mice it inhibits the apparent tumour-promoting effects and reduces the spread of cancer by 90%.
Said Dr Singleton, assistant professor of medicine at the University of Chicago Medical Center and principal author of the research: “If confirmed clinically, this could change how we do surgical anaesthesia for our cancer patients.”
Cancer Research UK said more tests were needed before any changes in treatment.
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American Association for Cancer Research