Trends in development of various types of lung cancer after cessation of smoking

Aim: this research aims at categorizing the different types of lung cancer in patient population unique to pakistan and providing an insight in the occurrence of various histological subtypes relative to the patient's smoking status. study design: cross-sectional study. study setting and duration: february to june 2015 at four major hospitals of lahore methods: all diagnosed cases of lung cancer presenting between january 2013 to december 2014 were considered eligible for the study. a questionnaire regarding smoking status,particulars of the disease and risk factors was filled either by accessing patient records or contacting the patient/next of kin. statistical analyses were performed using ibm's spss,version 24.0. results: 229 patients were considered eligible for the study. the study population consisted of 84.3% males and 15.7% females. univariate analyses showed that the non-smokers were more likely to have adenocarcinoma (63.6%) vs. 28.8% for ever-smokers. small cell lung cancer and squamous cell carcinoma were more common among smokers (18.4% and 39.3%) vs. 6.1% and 27.3% for non-smokers respectively. among ex-smokers histopathologies observed were 23.7% adenocarcinoma,7.9% small cell lung cancer(sclc),47.4% squamous cell carcinoma(scc) and 21.1% cases of non-specified non-small cell lung cancer(nsclc). as the time period since quitting increased,in case of ex-smokers in our study population,the number of cases who presented with both non-small cell lung cancers and small cell lung cancer continue to increase reaching peak level at five years followed by a sharp decline. conclusion: the histopathology of lung cancer varied with smoking status. adenocarcinoma was a predominant finding in non-smokers while sclc and scc showed a stronger association with ever-smokers,showing a continuous rise with increasing pack years. in our study,we conclude that risk of lung cancer continues to rise till five years after cessation of smoking and it may be protective of lung cancer after 10 years of quitting.