title: Smoking habits are an independent prognostic factor in patients with lung cancer.
abstract: OBJECTIVE
  The role of tobacco in the pathogenesis of lung cancer (LC) has been clearly established. Based on the epidemiological evidence that smoking may influence LC progression, we investigated the idea that smoking behavior could be associated with overall survival (OS) in this group of patients.
  
  
  METHODS
  A total of 351 patients with LC (311 men and 40 women) were reviewed. Smoking status was assessed as tobacco users or non-users. To calculate pack-years of smoking, the average of number of cigarettes smoked per day was divided by 20 to give packs per day, and then multiplied by the total number of years of smoking. OS was the main outcome measure.
  
  
  RESULTS
  The mean follow-up was 3.3 ± 1.2 years. Kaplan-Meier plots of OS by use of tobacco revealed significant differences by smoking status (log-rank = 5.44, P < 0.01), indicating a reduced survival rate in tobacco users. The effect on OS of the amount of cigarette smoking was also evident when we subdivided the former and current smokers into ≤7 (mean value) pack-years and >7 pack-years groups (log-rank = 4.27, P < 0.05). After adjusting for all potential confounders, tobacco smoking retained its independent prognostic significance for OS (hazard ratio = 1.53, 95% confidence interval = 1.19-2.17, P = 0.02).
  
  
  CONCLUSIONS
  Our data indicate that cigarette smoking is significantly associated with a poor prognosis among patients diagnosed with LC in a dose-dependent manner.
authors.affiliation: Department of Medical Oncology, State Hospital, Balikesir, Turkey.
authors.forename: Nilufer
authors.initials: N
authors.lastname: Avci
authors.affiliation: Department of Radiation Oncology, State Hospital, Balikesir, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Hayar
authors.affiliation: Department of Radiation Oncology, State Hospital, Balikesir, Turkey.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Altmisdortoglu
authors.affiliation: Department of Medical Oncology, Mugla Sitki Kocman University Faculty of Medicine, Mugla, Turkey.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Tanriverdi
authors.affiliation: Department of Medical Oncology, Uludag University Faculty of Medicine, Bursa, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Deligonul
authors.affiliation: Department of Medical Oncology, State Hospital, Balikesir, Turkey.
authors.forename: Cetin
authors.initials: C
authors.lastname: Ordu
authors.affiliation: Department of Medical Oncology, Uludag University Faculty of Medicine, Bursa, Turkey.
authors.forename: Turkkan
authors.initials: T
authors.lastname: Evrensel
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology / Q000639:trends; D016019:Survival Analysis
keywords: lung cancer - smoking - pack-years - prognosis