Multistage carcinogenesis and lung cancer mortality in three cohorts.
Experimental evidence indicates that tobacco smoke acts both as an initiator and a promoter in lung carcinogenesis. We used the two-stage clonal expansion model incorporating the ideas of initiation, promotion, and malignant conversion to analyze lung cancer mortality in three large cohorts, the British Doctors' cohort and the two American Cancer Society cohorts, to determine how smoking habits influence age-specific lung cancer rates via these mechanisms. Likelihood ratio tests indicate that smoking-related promotion is the dominant model mechanism associated with lung cancer mortality in all cohorts. Smoking-related initiation is less important than promotion but interacts synergistically with it. Although no information on ex-smokers is available in these data, the model with estimated variables can be used to project risks among ex-smokers. These projected risks are in good agreement with the risk among ex-smokers derived from other studies. We present 10-year projected risks for current and former smokers adjusted for competing causes of mortality. The importance of smoking duration on lung cancer risk in these cohorts is a direct consequence of promotion. Intervention and treatment strategies should focus on promotion as the primary etiologic mechanism in lung carcinogenesis.
Hazelton
William D
WD
Fred Hutchinson Cancer Research Center, Public Health Sciences Division, M2-B500, 1100 Fairview Avenue North, Box 19024, Seattle, WA 98109-1024, USA. hazelton@fhcrc.org
Clements
Mark S
MS
Moolgavkar
Suresh H
SH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000570:American Cancer Society; D002273:Carcinogens / Q000633:toxicity; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008175:Lung Neoplasms / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D018570:Risk Assessment / Q000379:methods*; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D013997:Time Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014026:Nicotiana
D002273:Carcinogens; D014028:Tobacco Smoke Pollution