How smoking causes cancer

Everyone has known for decades that smoking can kill, but until now no one really understood how cigarette smoke causes healthy lung cells to become cancerous.

In a new study published in the March 2008 print issue of The FASEB Journal, researchers from the University of California, Davis, show that hydrogen peroxide (or similar oxidants) in cigarette smoke is the culprit.

Safer cigarettes
This finding may help the tobacco industry develop “safer” cigarettes by eliminating such substances in the smoke, while giving medical researchers a new avenue to develop lung cancer treatments.

“With the five-year survival rate for people with lung cancer at a dismally low 15.5 percent, we hope this study will provide better insight into the identification of new therapeutic targets,” said Tzipora Goldkorn, senior author of the report.

The researchers exposed different sets of human lung airway cells to cigarette smoke and hydrogen peroxide. After exposure, these cells were then incubated for one to two days. Then they were assessed for signs of cancer development and compared to unexposed airway cells.

The cells exposed to cigarette smoke and the cells exposed to hydrogen peroxide showed the same molecular signatures of cancer development, while the unexposed cells did not.

“Guns kill, bombs kill and cigarettes kill,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “While biologists can’t do much about the first two, studies like this will help in the fight against tobacco-related death and disease. These experiments not only pin-point new molecular targets for cancer treatment, but also identify culprits in cigarette smoke that eventually will do the smoker in.”

43 known carcinogens
In 2000 a US Surgeon General report revealed that tobacco smoke contains more than 4 000 chemical compounds, with 43 being known carcinogens.

Some of the 4 000 compounds result from chemicals added in processing to improve taste, increase burning times, and prolong shelf life.

Apart from lung cancer, smoking is known to increase the risk of heart disease, stroke, macular degeneration, erectile dysfunction, breast cancer and mouth cancer, among others.

– (EurekAlert/Health24)

Read more:
Stop smoking Centre

February 2008

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