Objective To compare the hazards of cigarette smoking in men who formed their habits at different periods, and the extent of the reduction in risk when cigarette smoking is stopped at different ages. Design Prospective study that has continued from 1951 to 2001. Setting United Kingdom. Participants 34 439 male British doctors. Information about their smoking habits was obtained in 1951, and periodically thereafter; cause specific mortality was monitored for 50 years. Main outcome measures Overall mortality by smoking habit, considering separately men born in different periods. Results The excess mortality associated with smoking chiefly involved vascular, neoplastic, and respiratory diseases that can be caused by smoking. Men born in 1900-1930 who smoked only cigarettes and continued smoking died on average about 10 years younger than lifelong non-smokers. Cessation at age 60, 50, 40, or 30 years gained, respectively, about 3, 6, 9, or 10 years of life expectancy. The excess mortality associated with cigarette smoking was less for men born in the 19th century and was greatest for men born in the 1920s. The cigarette smoker versus non-smoker probabilities of dying in middle age (35-69) were 42% v 24% (a twofold death rate ratio) for those born in 1900-1909, but were 43% v 15% (a threefold death rate ratio) for those born in the 1920s. At older ages, the cigarette smoker versus non-smoker probabilities of surviving from age 70 to 90 were 10% v 12% at the death rates of the 1950s (that is, among men born around the 1870s) but were 7% v 33% (again a threefold death rate ratio) at the death rates of the 1990s (that is, among men born around the 1910s). Conclusion A substantial progressive decrease in the mortality rates among non-smokers over the past half century (due to prevention and improved treatment of disease) has been wholly outweighed, among cigarette smokers, by a progressive increase in the smoker v non-smoker death rate ratio due to earlier and more intensive use of cigarettes. Among the men born around 1920, prolonged cigarette smoking from early adult life tripled age specific mortality rates, but cessation at age 50 halved the hazard, and cessation at age 30 avoided almost all of it.

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Objectives A four-stage model of the cigarette epidemic was proposed in 1994 to communicate the long delay between the widespread uptake of cigarette smoking and its full effects on mortality, as had been experienced in economically developed countries where cigarette smoking became entrenched decades earlier in men than in women. In the present work, the question of whether qualitative predictions from the model have matched recent trends in smoking and deaths from smoking in countries at various levels of economic development is assessed, and possible projections to the year 2025 are considered.Methods The proportion of all deaths attributed to tobacco was estimated indirectly for 41 high-resource and medium-resource countries from 1950 to the most recent year for which data were available, generally about 2005e2009. The trends in tobacco-attributed mortality in later middle age were then projected forward to 2025, based on recent trends in tobacco-attributed mortality in early middle age. Results In developed countries the prevalence of smoking has continued to decrease in both sexes, although the rate of decrease has slowed and is less than that predicted by the original version of the model. Over the past 20 years the proportionate contribution of smoking to all deaths has decreased in men while continuing to increase or plateau among women. Although the proportion of all deaths at ages 35e69 that are attributed to smoking is still generally greater in men than in women, the male and female proportions are converging and will probably cross over in some high resource countries. Projections through to 2025 suggest that male and female smoking prevalence and smokingattributed mortality will decrease in parallel in most developed countries towards lower limits that are not yet defined. In developing countries the model seems generally applicable to men but cannot predict whether or when women will begin smoking in large numbers. Modified criteria that describe the stages of the epidemic separately for men and women would be more generalisable to developing countries. Conclusions The four-stage model of the cigarette epidemic still provides a reasonably useful description in many developed countries. Its relevance to developing countries could be improved by describing the stages of the epidemic separately for men and women.

Objective To assess the hazards at an early phase of the growing epidemic of deaths from tobacco in China. Design Smoking habits before 1980 (obtained from family or other informants) of 0.7 million adults who had died of neoplastic, respiratory, or vascular causes were compared with those of a reference group of 0.2 million who had died of other causes. Setting 24 urban and 74 rural areas of China. Subjects One million people who had died during 1986-8 and whose families could be interviewed. Main outcome measures Tobacco attributable mortality in middle or old age from neoplastic, respiratory, or vascular disease. Results Among male smokers aged 35-69 there was a 51% (SE 2) excess of neoplastic deaths, a 31% (2) excess of respiratory deaths, and a 15% (2) excess of vascular deaths. All three excesses were significant (P < 0.0001). Among male smokers aged >70 there was a 39% (3) excess of neoplastic deaths, a 54% (2) excess of respiratory deaths, and a 6% (2) excess of vascular deaths. Fewer women smoked, but those who did had tobacco attributable risks of lung cancer and respiratory disease about the same as men. For both sexes, the lung cancer rates at ages 35-69 were about three times as great in smokers as in non-smokers, but because the rates among non-smokers in different parts of China varied widely the absolute excesses of lung cancer in smokers also varied. Of all deaths attributed to tobacco, 45% were due to chronic obstructive pulmonary disease and 15% to lung cancer; oesophageal cancer, stomach cancer, liver cancer, tuberculosis, stroke, and ischaemic heart disease each caused 5-8%. Tobacco caused about 0.6 million Chinese deaths in 1990 (0.5 million men). This will rise to 0.8 million in 2000 (0.4 million at ages 35-69) or to more if the tobacco attributed fractions increase. Conclusions At current age specific death rates in smokers and non-smokers one in four smokers would be killed by tobacco, but as the epidemic grows this proportion will roughly double. If current smoking uptake rates persist in China (where about two thirds of men but few women become smokers) tobacco will kill about 100 million of the 0.3 billion males now aged 0-29, with half these deaths in middle age and half in old age.