Why Does Smoking Cause Lung Cancer?

It's about hydrogen peroxide

Each year, 4 million people die because of diseases caused by tobacco smoking, one person every 8 seconds. Tobacco smoking is the most important cause of diseases worldwide. If the current tendency is maintained, by 2020 smoking will kill more persons than AIDS, tuberculosis, maternal mortality, car accidents, suicides and murder do. Still, one third of the adults worldwide smoke.

About 20% of the American deaths are connected to tobacco ( 400,000 cases annually). Smoking is the culprit for 90% of all lung cancer deaths in men and 80% in women. The tobacco smoke contains over 4,000 molecules, but only 43 are known to cause cancer. Some of these chemicals are added through processing for improving taste, increasing burning times, and prolonging shelf life.

A new study published in the "The FASEB Journal" and led by a team from the University of California, Davis, points that hydrogen peroxide (or other oxidants) in cigarette smoke turn the healthy lung cells to cancerous ones. Tobacco industry could make healthier cigarettes by removing these chemicals, while lung cancer treatments would find new methods.

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

In the lab, the team exposed various sets of human lung cells to cigarette smoke and hydrogen peroxide. After that, the lung cells were incubated for one to two days. These cells were then assessed for signs of cancer development together with non-exposed lung cells. Cells exposed to cigarette smoke or hydrogen peroxide had the same molecular pathways of cancer, while the non-exposed cells did not.

"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," said Gerald Weissmann, MD, Editor-in-Chief of "The FASEB Journal."

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