About Lung Cancer
According to the American Lung Association, cigarette smoking is the top source of preventable disease and death worldwide. An estimated 438,000 Americans die from smoking-related illnesses each year, and smoking is directly linked to approximately 90 percent of lung cancer deaths.
Lung cancer occurs when normal, healthy cells within the lungs become damaged and mutate. Normally, the immune system destroys damaged and mutated cells, but if the cells mutate faster than the immune system can keep up, cancers form. Cigarette smoke has several chemicals that are known to damage lung cells and cause cancer.
Carcinogens in Tobacco Smoke
By the American Lung Association's estimation, tobacco smoke contains 69 known carcinogens, one of which is benzene.
Benzene is a colorless, flammable chemical often used in manufacturing. According to the Centers for Disease Control, cigarette smoke is a major source of benzene exposure. Cigarette manufacturers add benzene to cigarettes as a burning agent. Burning agents make it easier to draw smoke into the lungs and make the cigarettes burn down faster---so that people smoke more. Benzene is a carcinogen because it causes cells to stop working properly. Benzene may damage the lung cells directly and affect the immune system by causing the loss of white blood cells and antibodies. Certain white blood cells destroy cancer cells.
Formaldehyde is another known carcinogen in cigarettes, and researchers are still studying exactly how formaldehyde works in causing cancers.
How Cigarette Smoke Causes Cancer
In May 2008, researchers at the Oregon Health and Science University isolated a protein believed to cause the genetic changes that lead to lung cancer. The protein FANCD2 is a caretaker protein that normally prevents cancer by correcting DNA damage and killing faulty or mutated cells. According to Laura Hays, Ph.D., research assistant professor of medicine and the senior author of the study, cigarette smoke slows the production of FANCD2 and other caretaker proteins. Lower levels of FANCD2 proteins pave the way for DNA damage. The damaged DNA then causes cell mutations. If enough cells mutate, and reproduce, cancer forms.
FANCD2 is part of a family of proteins associated with a genetic condition called Fanconi anemia. Patients with Fanconi anemia are more likely to develop cancers at an early age and have lower levels of the FANCD2 family of proteins.
