[The prevalence of cytostatic-resistant lung tumors in smokers]

The resistance of tumours against doxorubicin was determined in vitro and compared with their smoking habits in 94 patients (81 males and 13 females; mean age 59 [38-76] years) with non-small-cell lung tumour. Among non-smokers (n = 22) 11 tumours were resistant and 11 sensitive, while among smokers (n = 72) 57 (79%) were resistant and only 15 (21%) sensitive to doxorubicin. P-glycoprotein was measured immunohistochemically and with the monoclonal antibody JSB-1 in order to test whether there is a relationship between the prevalence of resistant tumours among smokers and the expression of P-glycoprotein. Among 22 nonsmokers only two tumours (9%) were P-glycoprotein positive, but among 72 smokers, 42 tumours (58%) were positive (P less than 0.0001). Thus, the increased amount of resistant non-small-cell lung tumours in smokers can be explained partially by an increased expression of P-glycoprotein.