Morphine Found to Stimulate Breast Tumors

Researchers have found that morphine stimulates signals in endothelial cells that in turn prompt tumors to increase in mice. Their study was published in the August 1, 2002, issue of Cancer Research.

Morphine is routinely given to cancer patients to manage severe pain. The researchers found that doses of morphine similar to doses given to cancer patients activate the mitogen-activated protein kinase (MAPK) signaling pathway in human endothelial cells. MAPK plays a key role in promoting the multiplication and angiogenesis of endothelial cells. They also found that morphine promotes endothelial cell survival by activating Akt, the key survival-signaling pathway inside these cells. The survival of endothelial cells is critical to the angiogenesis process.

"Our study shows that morphine stimulates the formation of new blood vessels inside the tumor, which in turn allows increased growth of tumors in mice,” said Kalpna Gupta, Ph.D., assistant professor of medicine and lead author of the study conducted at the University of Minnesota Cancer Center. Morphine did not promote initial or early growth of tumors, noted Dr. Gupta, and there is no scientific data at this time indicating that morphine or similar pain medications will lead to increased growth of cancers in humans. Further investigation is needed.




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