Smoking and Disease: Prospects for Control

Our plain-English summary of Smoking and Disease: Prospects for Control, by R. Doll (1977).

The study

• Author: R. Doll
• Published: Royal Society of Health Journal, Volume 4. August 1977
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1977 address to the Health Congress in Eastbourne is about tobacco smoking and does not discuss asbestos. The author drew on a 20-year study of about 34,000 male British doctors, published in 1976, and on national death statistics. Among the doctors, 20 diseases or groups of diseases were associated with smoking. From non-smokers to heavy cigarette smokers, death rates rose 46 times for chronic bronchitis and pulmonary heart disease and 25 times for lung cancer. Ischaemic heart disease deaths rose by two-thirds overall, but 15 times under age 45 and about 40 per cent over 65. In ex-smokers, rates approached but never quite equalled those of lifelong non-smokers. The doctors cut their smoking from 9.1 to 3.6 cigarettes a day, and their rates of these diseases fell relative to national rates. Nationally, men's lung cancer death rate fell very slightly in 1975, for the first time in fifty years. The author believed smoking was responsible for 70 to 90 per cent of the mortality difference between smokers and non-smokers. The author judged it uncertain whether lower-tar cigarettes reduce coronary thrombosis risk.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Published lecture (inaugural address) reviewing evidence on smoking and disease. It draws mainly on the author's prospective study of British doctors (Doll and Peto, 1976) and on national mortality and tobacco sales trends.
• Who was studied: About 34,000 male British doctors who answered a smoking questionnaire in 1951 and were followed for 20 years; also national mortality data for England and Wales, 1951 to 1974/1975
• Exposure: Cigarette smoking (grouped as non-smokers and 1-14, 15-24, or 25 or more cigarettes a day), plus changes in smoking habits, filter-tipped cigarettes and tar and nicotine yields. No asbestos exposure was studied.
• Main results:
  • Among the doctors, the mortality of men who began smoking cigarettes under 25 years of age and smoked only cigarettes was about double that of lifelong non-smokers throughout middle age
  • Among the doctors, 20 diseases or groups of diseases were associated with smoking
  • Among the doctors, from non-smokers to heavy cigarette smokers, mortality rose 46 times for chronic bronchitis and pulmonary heart disease, 25 times for lung cancer, and by only two-thirds for ischaemic heart disease
  • For ischaemic heart disease among the doctors, mortality increased 15 times from non-smokers to heavy cigarette smokers under 45 years of age, 3 times at 45 to 54, twice at 55 to 64, and by only about 40 per cent over 65
  • Lung cancer, chronic bronchitis and ischaemic heart disease together accounted for nearly 40 per cent of all observed deaths among the doctors
  • In doctors who had stopped smoking, the death rate fell compared with men of the same ages who continued to smoke. It approached, but never quite equalled, the rate in lifelong non-smokers.
  • Taken together, the collaborating doctors reduced their consumption from 9.1 to 3.6 cigarettes a day
  • For each of the three main smoking-related diseases, the doctors' death rate as a percentage of the national rate became relatively less with time. For coronary thrombosis the reduction was substantial under 54 years of age but only very slight at 65 to 84.
  • Nationally, the total lung cancer death rate in men decreased very slightly in 1975 for the first time in fifty years. In women, total lung cancer mortality was still increasing by about 5 per cent a year.
  • The sales-weighted mean yield per cigarette in the United Kingdom fell over ten years by 43 per cent for tar and 35 per cent for nicotine
  • The author judged it uncertain whether the lower-tar cigarettes then mainly smoked produce less risk of coronary thrombosis
• The authors' conclusion: The author stated a belief that smoking is responsible for between 70 and 90 per cent of the difference in mortality between cigarette smokers and non-smokers
• Limitations the authors state:
  • The doctors who answered the first questionnaire were a self-selected sample that tended to exclude seriously ill men, so the first three years of observation were excluded from the trend analysis
  • Comparing changes in smoking with changes in national mortality is complex and can be grossly misleading. Diagnosis, death classification, treatment and other causes such as air pollution and diet all changed over the same period.
  • Men do not give up smoking at random; some stopped because of increasing shortness of breath, which affects death rates in ex-smokers

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer.

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