Researchers at Stanford University found that use of smoking-cessation products may increase the risk of cancer, HealthScout reported June 29.In studying nicotine's effect on human cells and on the growth of blood vessels that feed tumors, researchers expected to confirm that nicotine impairs the growth of new blood vessels.
Instead, they found that when exposed to nicotine, human endothelial cells, which line blood vessels, dramatically increase the number of times they divide. Furthermore, nicotine interferes with the natural cycle of cell death.
After giving nicotine to mice with certain types of human cancers, the researchers found that the number of new blood vessels supplying tumors increased, and the tumors grew.
"The cells that line our vessels have receptors on their surface for nicotine," said Dr. John Cooke, associate professor of cardiovascular medicine, who led the study. "When they're exposed to nicotine they get stimulated. They started to divide, they proliferate, they multiply, and they migrate and they form tubes."
He added that, "Nicotine is as potent as any growth factor that's been looked at" in triggering formation of new blood vessels.
The researchers discovered that when growth factors are given systemically, rather than targeted to a specific area where vessel formation is desired, they could promote tumor growth. "The same thing is true of nicotine. Nicotine, if given systemically, could have unwanted consequences," Cooke said.
For people using nicotine patches, sprays, or gum to quit smoking, or for patients receiving nicotine-based treatments for Alzheimer's and other diseases, Cooke recommends weighing the risks and the benefits.
"If I was a smoker, I would still use nicotine patches or gum. I would use anything I could to stop smoking," said Cooke. "For the short term, nicotine therapy has been shown to be safe and effective in getting people off of cigarettes, and it's an important adjunct to stop-smoking programs."
But he warned that people who misuse nicotine patches by relying on them chronically "could have unwanted consequences."
The study is published in the July issue of Nature Medicine.
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