Association Between Smoking and Lung Cancer

followed฀from฀1971฀to฀1995.฀The฀risk฀OR฀for฀oropharyngeal฀cancer฀increased฀to฀2.02฀and฀ for฀lung฀cancer฀to฀2.14฀ [7] .฀Despite฀the฀fact฀that฀they฀continued฀smoking,฀cigarette฀smokers฀ who฀switched฀to฀cigar฀or฀pipe฀had฀a฀somewhat฀reduced฀risk฀of฀lung฀cancer฀than฀would฀have฀ been฀the฀case฀if฀they฀had฀continued฀smoking฀cigarettes,฀but฀switching฀tobacco฀products฀did฀ not฀enable฀them฀to฀achieve฀the฀lower฀risk฀level฀of฀ex-smokers฀ [57] . On฀the฀contrary,฀despite฀suspicions,฀mentholated฀cigarettes,฀which฀are฀smoked฀in฀pref- erence฀in฀some฀countries,฀do฀not฀entail฀any฀additional฀risk฀for฀bronchial฀carcinoma฀ [58] . Lung฀cancer฀is฀the฀most฀important฀risk฀factor฀for฀women,฀more฀so฀than฀for฀men.฀The฀risk฀ increases฀in฀line฀with฀the฀dose฀i.e.,฀the฀number฀of฀cigarettes฀smoked฀and฀is฀not฀lowered฀by฀ dietary฀factors฀b-carotene.

5.2.2 Types of Lung Cancer

Smoking฀encourages฀the฀development฀of฀all฀types฀of฀lung฀cancer:฀SCC,฀AC,฀small฀cell฀car- cinoma฀and฀undifferentiated฀carcinoma.฀In฀this฀last฀category,฀the฀origin฀of฀the฀cells฀฀cannot฀ Fig. 5.2 ฀฀฀Endoscopic฀view฀of฀an฀occluding฀ bronchial฀carcinoma฀after฀laser฀coagulation฀has฀ already฀been฀initiated฀in฀a฀55-year-old฀patient฀ with฀a฀25-year฀history฀of฀smoking฀by฀kind฀ permission฀of฀Prof.฀Drings,฀Heidelberg Fig. 5.3 ฀฀฀Large฀adenocarci- noma฀of฀the฀right฀superior฀ lobe฀following฀surgical฀ resection฀from฀a฀63-year-old฀ smoker฀surgery฀performed฀ by฀Prof.฀Vogt-Moykopf,฀ Heidelberg be฀identiied฀ [17,฀59] .฀Whereas฀SCC฀used฀to฀be฀the฀predominant฀type,฀for฀about฀the฀last฀10฀ years,฀it฀has฀been฀overtaken฀by฀AC,฀with฀small฀cell฀and฀undifferentiated฀carcinoma฀in฀third฀ and฀fourth฀positions฀ [60] .฀The฀change฀in฀incidence฀is฀thought฀to฀be฀due฀to฀the฀switch฀to฀low- tar฀and฀low-nicotine฀cigarette฀brands฀ [61] ฀where฀inhalation฀depth฀and฀frequency฀and฀nitro- samine฀ exposure฀ are฀ increased฀ [62] .฀ As฀ a฀ result,฀ smaller,฀ less฀ well-protected฀ bronchial฀ 0.6 0.5 0.4 0.3 0.2 0.1 0.0 I-Hydroxypyrene [µg24 h] All subjects Nonsmokers Smokers 42 27 27 15 15 12 suburban rural a 0.00 0.05 0.10 0.15 0.20 0.25 All subjects [fmolmg] Nonsmokers Smokers b c All subjects Nonsmokers Smokers 0.00 0.03 0.06 0.09 0.12 0.15 Fig. 5.4 ฀฀฀Renal฀excretion฀of฀ von฀1-hydroxypyrene฀a,฀ benzo[a]pyrene฀adducts฀of฀ haemoglobin฀b฀and฀of฀ albumin฀c฀in฀42฀ ฀non-smokers฀and฀27฀ smokers,฀classiied฀by฀ suburban฀or฀rural฀location฀of฀ residence.฀The฀vertical฀lines฀ show฀the฀standard฀error฀of฀ the฀mean.฀p฀=฀0.056฀ [55]