During most of the 20th Century, the disease risks from cigarette smoking have increased in the United States, first among male smokers and later among female smokers. Two new studies attempted to determine recent trends regarding smoking among men and women in the United States. The studies noted an alarming increase in smoking-related deaths among women. However, on a brighter side, one of the studies noted how both men and women can avoid a premature death from smoking. Both studies were published on January 24 in the New England Journal of Medicine by international teams of researchers.
Smoking currently accounts for almost 200,000 deaths annually in the US, or about one fourth of all deaths in this age group. The disease risks from cigarette smoking increased over most of the 20th century in the United States as successive generations of first male and then female smokers began smoking at progressively earlier ages. American men began smoking manufactured cigarettes early in the 20th century; by the 1930s, the average age that people began smoking fell below 18 years. Before World War II, relatively few women smoked regularly; however, the age they began smoking continued to decrease through the 1960s. Women were not included in the earliest prospective epidemiologic studies in the 1950s because mortality from lung cancer among women was not yet increasing in the general population. In 1964, the link between smoking and lung cancer was released in the 1964 US Surgeon General’s Report. It concluded that “cigarette smoking is causally related to lung cancer in men.” However, at that time, neither sex had yet experienced the full effects of smoking from adolescence throughout adulthood.
One study included information from more than 2.2 million adults ages 55 and older. It measured temporal trends in mortality across three time periods (1959–1965, 1982–1988, and 2000–2010), comparing absolute and relative risks according to sex and self-reported smoking status. In the 1960s, female smokers were 2.7 times more likely to die from lung cancer compared with women who did not smoke. By the 1980s, women who smoked were 12.6 times more likely to die from lung cancer, and in the 2000s, they were 25.7 times more likely to die from lung cancer, the study found. The study authors noted that the dramatic increase reflects changes in smoking patterns among women that began in the 1960s. (Because lung cancer takes years to develop, changes in smoking patterns would not start to influence deaths until many years later.) In the '60s, more women started smoking during their teenage years (a trend that men had already embraced during the 1930s). The number of cigarettes smoked per day was highest in men in the 1970s and highest in women in the 1980s. The researchers noted that their findings confirm the prediction that “women who smoke like men die like men.”
The other study also evaluated smoking trends among men and women in the US and also evaluated the benefits of quitting and found it to be huge, particularly for those who quit before the age of 40. The study group comprised 113,752 women and 88,496 men 25 years of age or older who were interviewed between 1997 and 2004 in the US National Health Interview Survey (NHIS). Enrollment rates for women exceeded those of men. Smoking and smoking-cessation histories were obtained from the subjects and that data was correlated to the causes of deaths that occurred by December 31, 2006 (8,236 deaths in women and 7,479 deaths in men). Hazard ratios for death among current smokers, as compared with those who had never smoked, were adjusted for age, educational level, adiposity, and alcohol consumption.
The researchers found that for participants who were 25 to 79 years of age, the rate of death from any cause among current smokers was about three times that among those who had never smoked (hazard ratio for women: 3.0; hazard ratio for men: 2.8; 99% CI). They noted that most of the excess mortality among smokers was due to neoplastic (cancer), vascular (blood vessel), respiratory (lungs), and other diseases that can be caused by smoking. The probability of surviving from 25 to 79 years of age was approximately twice as high in individuals who had never smoked, compared to current smokers (70% vs. 38% among women; 61% vs. 26% among men). Compared to individuals who never smoked, life expectancy was shortened by more than 10 years among the current smokers. Compared to individuals who continued to smoke, adults who had quit smoking at 25 to 34, 35 to 44, or 45 to 54 years of age gained about 10, 9, and 6 years of life, respectively.
The authors concluded that, compared to individuals who never smoked, smokers lose at least one decade of life expectancy. They stressed that cessation before the age of 40 years reduces the risk of death associated with continued smoking by about 90%.