How Smoking Causes Cancer

There's no question about it: smoking causes cancer. In fact, smoking is responsible for almost 90 percent of all lung cancer deaths, and lung cancer is the leading cause of cancer death in the U.S. Roughly 22 percent of cancer deaths in women, and 45 percent in men, are directly attributable to personal smoking habits.

Smoking is an established cause of cancers of the lungs, larynx, oral cavity, esophagus, and bladder, and a probable cause of kidney, pancreatic, stomach, breast, colon, prostate, and cervical cancer. It reduces the effectiveness of cancer treatment and increases your risk of developing a secondary cancer.

How Smoking Causes Cancer

Toxic ingredients. There are more than 4,000 chemicals in tobacco smoke; about 250 are harmful, and at least 50 are carcinogenic (cancer causing).

The three main ingredients in tobacco smoke are

  • Tar
  • Nicotine
  • Carbon dioxide

Yes, the tar in cigarettes is the same stuff we use to pave our roads. It clumps together to provide a solid road surface-and produces a similar result in your lungs, clogging your airways. Nicotine does not directly cause cancer, but it does make smoking addictive and very difficult to quit. Carbon dioxide is the gas that also spews from your car exhaust. It robs your muscles, brain, and tissues of oxygen; it makes your heart work harder; and it causes your airways to swell.

As if this cocktail of toxic chemicals wasn't deadly enough, tobacco smoke also contains:

  • Acetone (used in nail polish and paint removers)
  • Ammonia (used in dry cleaning), arsenic (used in pest control)
  • Benzene (used in fuel)
  • Naphthalene (used in mothballs)

Physiological changes. Tobacco smoke causes genetic and cellular changes. It alters critical cell pathways that foster uncontrolled growth and spread of cancer cells. Tobacco also causes immediate inflammation in your tissues, especially the lining of your lungs. Over time, the continuous assault from smoking weakens your body's ability to heal itself.

Smokers aren't the only ones who suffer. Nonsmokers increase their risk of lung cancer by 20 to 30 percent when they live with a smoker.

According to the National Cancer Institute, quitting smoking has major and immediate health benefits, including reducing your risk of developing lung and other cancers. Ten years after you quit smoking, you reduce your risk of lung cancer by one-third or more.

Smoking is the number one preventable cause of death in the United States-and it is directly within your control.



Quit4Life. "Smoking and its Effects on Smokers." Web.

American Cancer Society. "Questions About Smoking, Tobacco, and Health." Web. 27 June 2011.

U.S. Department of Health and Human Services. "EXPOSURE TO TOBACCO SMOKE CAUSES IMMEDIATE DAMAGE, SAYS NEW SURGEON GENERAL'S REPORT." Press release. Web. 9 December 2010.

Office of the Surgeon General. "How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease." Pages 325 - 350. Web.

Nelson, Roxanne. "Impact of Smoking on Breast Cancer Risk Greater Than Thought." Medscape Medical News. Web. 24 May 2011,

National Cancer Institute. "Smoking Cessation and Continued Risk in Cancer Patients (PDQ®)." Web. 11 July 2011.