The relation between various histological types of lung cancer and the number of years since cessation of smoking.

We studied the relation between various histological types of lung cancer and the number of years of cessation from smoking using data from a recently completed case-control study in Northern Germany. In this context we wanted to answer the question whether smoking cessation is a specific symptom of small cell lung cancer. Defining current smokers as the reference group the odds ratios decreased with years of cessation. Based on the analysis of all male cases and controls in our study, former smokers who stopped smoking 6-10 years ago had an odds ratio of 0.97 (95% confidence interval (C.I.) = 0.65-1.45), ex-smokers with 11-20 years of smoking cessation had a reduced risk of 0.55 (95% C.I. = 0.38-0.79), and for more than 20 years of cessation we found an odds ratio of 0.25 (95% C.I. = 0.16-0.40). Moreover, these calculations are also presented for the major groups of histological types of lung cancer. Our data show that there is no evidence for the presumption that cases with small cell lung cancer stop smoking earlier than cases with other histological types: in no other histological category we found such a big part of current smokers.