04 Links between Smoking and Lung Disease


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04 Links between Smoking and Lung Disease

  1. 1. Proving the Links betweenSmoking and Lung DiseaseEpidemiological and Experimental Evidence ALBIO9700/2006JK
  2. 2. Epidemiological Evidence Epidemiology: the study of patterns of disease in populations and the factors that influence the spread of disease Epidemiologist discovered a correlation between lung cancer and cigarette smoking Number of cigarettes Annual death rate per smoked per day 100 000 men 0 10 1-14 78 15-24 127 >25 251 Results of study carried out on male doctors in Britain ALBIO9700/2006JK
  3. 3.  General:  Up to 50% of smokers may die of smoking-related disease  Tobacco smoking is currently responsible for ~30% of all cancer deaths in developed countries  Estimated to account for ~4–5 million deaths a year worldwide  Projected to increase to ~10 million a year by 2030. Thus, if current smoking patterns continue, there will be >1 billion deaths attributable to tobacco smoking in the 21st century compared with ~100 million deaths in the 20th century ALBIO9700/2006JK
  4. 4.  The only other causes of disease with such rapidly increasing impact are those associated with HIV infection and, perhaps, obesity in Western countries Smokers are 3 times more likely to die in middle age than are non-smokers ALBIO9700/2006JK
  5. 5.  Chronic obstructive pulmonary disease:  Rare in non-smokers  90% of deaths from chronic obstructive pulmonary disease are attributed to smoking  98% of people with emphysema are smokers  20% of smokers suffer from emphysema  Deaths from pneumonia and influenza are twice as high among smokers ALBIO9700/2006JK
  6. 6.  Lung cancer:  Smokers are 18 times more likely to develop lung cancer than non-smokers  1/3 of all cancer deaths are a direct result of cigarette smoking  25% of smokers die of lung cancer  Risk increase if smokers inhale; start young; increase the number of cigarettes smoked per day; use high tar cigarettes; smoke for a long time ALBIO9700/2006JK
  7. 7.  Conclusions drawn from epidemiological data could be criticised because they only show that there is an association between the two, not a causal link between them With smoking, it is possible to show direct link with lung cancer because smoking is the common factor in almost all cases (Royal College of Physicians – 1962, 1971, 1977, 1983 and 1992) Cigarette smoking is linked with other cancers ALBIO9700/2006JK
  8. 8. Experimental Evidence 2 lines of evidence:  Tumours similar to those found in humans develop in animals exposed to cigarette smoke  Beagles used in experiments to investigate the effect of cigarette smoke on the lungs in the 1960s  Carcinogens have been identified in tar  Chemicals extracted and analysed (benzyprene)  Cancerous growth on painted skin of mice ALBIO9700/2006JK
  9. 9. ALBIO9700/2006JK