Morphine Could Spread Cancer
Posted on December 3, 2009Laboratory tests suggest that morphine—a powerful painkilling narcotic that is often prescribed to relieve pain from surgery and tumors—could actually encourage the spread of cancer. Scientists say the opiate promotes the growth of new blood vessels, which deliver oxygen and nutrients to tumors.
Speaking at a meeting of the American Association for Cancer Research in Boston, the scientists also claim to have found a drug that counters this effect.
Dr. Patrick Singleton, assistant professor of medicine at the University of Chicago Medical Center and principal author of the research, told the meeting of experts that in laboratory tests, morphine not only strengthened blood vessels but also appeared to make it easier for cancers to invade other tissues and spread.
But he said this could be overcome by a drug called methylnaltrexone or MNTX, which was developed in the 1980s to prevent morphine-related constipation but was only recently approved in the US. It appears to work without interfering with the pain-relieving properties of the opiate.
In mice with lung cancer, MNTX inhibited the apparent tumor-promoting effects of opiates, and reduced the spread of cancer in the mice by 90 percent.
"If confirmed clinically, this could change how we do surgical anesthesia for our cancer patients," said Dr. Singleton. "It also suggests potential new applications for this novel class of drugs which should be explored."
The tests were started after his colleague, anesthetist Jonathan Moss, noted that several patients receiving this kind of opiate blocker survived longer than might be expected after surgery.
Dr. Laura Bell of Cancer Research UK said morphine has a long history of providing effective pain relief, and that more tests were needed before making any changes in treatment.
"Research in this area is in the early stages, so it’s too early to tell whether opiate-based painkillers have an effect on cancer growth. Much more research would be needed to justify changing the way opiates are used to treat people with cancer."
