problems in the study of occupation and smoking in relation to lung cancer

Abstract

UNG CANCER IN HUMANS is known to be as-L sociated with a number of factors. I t occurs more frequently among males, among smokers, particularly cigarette smokers, in urban areas, among certain occupations, and in certain age groups. In studying the effect of any one factor or suspected factor, it is obvious that other known associated factors must be taken into account. For example, is the increased incidence of lung cancer among cigarette smokers associated with cigarette smoking alone or is it due to the circumstance that people in certain occupations also smoke more? Are the excess mortality and incidence of lung cancer in urban areas due to a difference in smoking habits among urban populations or to a greater concentration of certain occupation groups in cities?