Farmers were harvesting tobacco crops eight thousand years ago. Its uses since that time have ranged from weather forecasting, appetite suppression, and pain relief, to the ceremonial smoking of the peace pipe and recreational use. Although tobacco was smoked and chewed in the United States back in the days of Columbus, it was not until the 1880s that smoking cigarettes became a widespread custom. At its peak in 1965, 52% of all adult men and 32% of all adult women in the United States routinely smoked. By the year 2001, smoking rates in the United States had decreased to 25.5% in men, and 21.3% in women.
The potential adverse health effects of smoking were suspected as far back as 1859. It was then that an evaluation of 68 patients with oral cavity cancer linked 66 of them with the practice of smoking tobacco through short-stemmed clay pipes. Epidemiological evidence of the potentially harmful effects of cigarette smoking continued to mount over the following years. Finally, in 1962, the Royal College of Physicians of London officially deemed smoking a serious threat to health; in 1964 the U.S. Surgeon General followed suit.
Health risks of cigarette smoking
By 2001, an estimated 450, 000 Americans died annually from diseases related to cigarette smoking. According to the American Cancer Society, 3, 000 non-smoking adults die each year of lung cancer from the effects of secondhand smoke. Pregnant women who smoke are more likely to give birth to low-weight babies, and smokers have increased rates of heart disease and respiratory problems.
In addition to those health risks, smokers are at a higher risk for the development of many types of cancer. In fact, 38% of all cancer deaths in men and 23% of all cancer deaths in women are believed to be attributed to cigarette smoking. As cigarette smoking becomes more prevalent in developing countries, the incidence of particular diseases, such as lung cancer, has also increased.
Cancers associated specifically with tobacco use include:
- Lung cancer: Smoking is now the primary modifiable risk factor for lung cancer. Tobacco was first linked to lung cancer in 1898, when it was theorized to be the cause for several cases of lung cancers in tobacco workers. Since then, studies have continued to document the relationship between smoking and lung cancer. Lung cancer incidence—the number of new cases diagnosed per year—closely follows smoking trends. As more and more women began to smoke, for example, the incidence of lung cancer in women also increased. By the late 1900s, 90% of lung cancer cases in men and 79% in women were believed to be related to smoking.
- Head and neck cancer: Smoking increases the risk of head and neck cancers. When tobacco is used in conjunction with alcohol, there is believed to be an even higher risk of these types of diagnoses. The precise mechanism of this relationship, known as a "synergistic effect, " is not yet well understood.
- Esophageal cancer: Smokers, particularly women smokers, are at an increased risk for developing esophageal cancer—a risk that increases with the quantity of cigarettes smoked per day.
- Pancreatic cancer: An estimated 22, 000 people die from pancreatic cancer each year, and an alarming 30% of these deaths are related to cigarette smoking.
- Colorectal cancer: Individuals who smoke cigarettes are more likely to develop polyps in the colon, which in turn increases the risk of colon cancer. There is also evidence that the risk of colon and/or rectal cancer increases with pack years for smokers. (Pack years are calculated by multiplying the number of packs of cigarettes smoked a day by the number of years smoked.)
- Stomach cancer: Although some studies have found no existing relationship between smoking and stomach cancer, others have shown an increased risk for smokers over the age of 50 years and a relationship between the disease and pack-years of smoking. More conclusive research is necessary to better understand the role that smoking plays in the development of stomach, or gastric, cancer.
- Bladder cancer: Smoking is believed to be related to 30-40% of all bladder cancers, most of which are of the transitional cell type. The risk of developing bladder cancer is believed to be related to the duration of smoking and inversely related to the age at which smoking began (that is, the younger a person is when he or she starts smoking, the higher the chances of developing bladder cancer).
- Cervical cancer: There appears to be a relationship between smoking and cervical cancer—the higher the "dose, " or amount smoked, the higher the likelihood of developing cervical cancer. Smoking is also associated with human papilloma virus infection, or HPV. Certain types of HPV can cause warts to develop in the genital area and cervix. These types of infections are a major cause of cervical cancer. Because of these overlapping relationships, the exact effect of smoking in cervical cancer needs further study.
- Breast cancer: Smoking is not yet a well-established risk factor for breast cancer: some studies indicate an increased risk among smokers, and others report a decreased risk among smokers. Genetic susceptibility to certain components of tobacco may explain the varying results, but more research is needed to better understand the relationship.
Although cancer is not always preventable, avoiding known risk factors, such as smoking, is an important part of prevention. The best approach to prevent disease is not to start smoking at all. However, even individuals who have smoked for years can decrease their risk of cancer and improve their health and well being by breaking the habit. Shortly after quitting smoking, a person will notice an improvement in their sense of taste and smell. After a smoke-free ten years, lung cancer risk declines by up to 50%. After 15 smoke-free years, an ex-smoker has the same risk of early death than a person who never smoked at all. Although quitting smoking does reduce the likelihood of cancer development, the risk depends upon the amount smoked, the number of years smoked, and whether or not a person is ill at the time of smoking cessation.
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Tamara L. Brown, R.N.