Cigarette smoking harms nearly every organ in the body,1,44 and smoking is the leading preventable cause of premature death in the United States. Although rates of smoking have declined, it is estimated that it leads to about 480,000 deaths yearly.1 Smokers aged 60 and older have a twofold increase in mortality compared with those who have never smoked, dying an estimated 6 years earlier.45 Quitting smoking results in immediate health benefits, and some or all of the reduced life expectancy can be recovered depending on the age a person quits.46
Although nicotine itself does not cause cancer, at least 69 chemicals in tobacco smoke are carcinogenic,1 and cigarette smoking accounts for at least 30 percent of all cancer deaths.22 The overall rates of death from cancer are twice as high among smokers as nonsmokers, with heavy smokers having a four times greater risk of death from cancer than nonsmokers.1
Foremost among the cancers caused by tobacco use is lung cancer. Cigarette smoking has been linked to about 80 to 90 percent of all cases of lung cancer, the leading cause of cancer death for both men and women, and it is responsible for roughly 80 percent of deaths from this disease.22,47 Smoking increases lung cancer risk five to tenfold, with greater risk among heavy smokers.48 Smoking is also associated with cancers of the mouth, pharynx, larynx, esophagus, stomach, pancreas, cervix, kidney, and bladder, as well as acute myeloid.1 Cigarette smoking is not the only form of tobacco use associated with cancers. Smokeless tobacco (see "Other Tobacco Products") has been linked to cancer of the pharynx, esophagus, stomach, and lung, as well as to colorectal cancer.49
In addition to cancer, smoking causes lung diseases such as chronic bronchitis and emphysema, and it has been found to exacerbate asthma symptoms in adults and children. Cigarette smoking is the most significant risk factor for chronic obstructive pulmonary disease (COPD).50 Survival statistics indicate that quitting smoking results in repair to much of the smoking-induced lung damage over time. However, once COPD develops, it is irreversible; COPD-related lung damage is not repaired with time.
Smoking also substantially increases the risk of heart disease, including stroke, heart attack, vascular disease, and aneurysm.51,52 Cardiovascular disease is responsible for 40 percent of all smoking-related deaths.53 Smoking causes coronary heart disease, the leading cause of death in the United States. Smoking is also linked to many other major health conditions—including rheumatoid arthritis, inflammation, and impaired immune function.1 Even young smokers aged 26 to 41 report reduced health-related quality of life compared with nonsmoking peers, according to a cross-sectional population study.54 Recent animal research also identified a pathway between the pancreas and a part of the brain active in nicotine intake, potentially linking cigarette smoking to the risk of developing Type 2 Diabetes.