Opioid-based drugs, such as morphine, that have been the gold standard for treatment of postoperative and chronic cancer pain may promote the growth and spread of cancer, two new studies suggest.
The research, published in the journal Anesthesiology, suggests doctors re-evaluate whether these common treatments do more harm than good and if alternatives should be developed to protect patients.
"Epidemiologic findings suggest that the type of anesthesia we do for cancer surgery influences recurrence rate, and laboratory studies demonstrate that opioids influence tumor progression and metastasis," said Dr. Jonathan Moss, in a commentary that accompanied the published studes. "These studies have caused anesthesiologists to re-evaluate how best to do anesthesia and pain control for cancer patients."
The two new studies – by the University of Chicago Medicine and the University of North Carolina Medical Center – provide strong evidence that morphine or the body's own opioids, such as endorphins, appear to have “a significant and direct proliferative effect on cancer cells” and may suppress the body’s immune system.
One study presented in the journal — led by Patrick Singleton, at the University of Chicago Medicine — found opioids already in the body can enhance the malignant tendencies of human lung cancer cells transplanted into mice, even without the addition of morphine.
A second study – by Dr. Andrey Bortsov, at the University of North Carolina -- of more than 2,000 breast cancer patients found women who were less sensitive to opioids were much more likely to be alive 10 years after cancer treatment than those who were not. Women with one copy of the protective mutation were nearly twice as likely to have survived; those with two copies were four times as likely.
Funding for the studies was provided by the National Cancer Institute.