title: Increased lung cancer risk among patients with pneumococcal pneumonia: a nationwide population-based cohort study.
abstract: BACKGROUND
  The possible effects of pneumonia on subsequent lung cancer have been reported, but no relevant publications have focused on the association between pneumococcal pneumonia and lung cancer. The purpose of this study was to perform a nationwide population-based cohort study to investigate the risk of lung cancer after pneumococcus infection.
  
  
  METHODS
  This nationwide population-based cohort study was based on data obtained from the Taiwan National Health Insurance Database. In total, 22,034 pneumococcal pneumonia patients and 88,136 controls, matched for age and sex, were recruited for the study from 1997 to 2010.
  
  
  RESULTS
  The incidence rate of lung cancer (28.2 per 1,000 person-years) was significantly higher in pneumococcal pneumonia patients than in controls (8.7 per 1,000 person-years; incidence rate ratio, 3.25; 95 % confidence interval, 3.09-3.42; p < 0.001). Cox proportional hazards regression analysis showed a hazard ratio of 4.24 (95 % confidence interval, 3.96-4.55) for the pneumococcal pneumonia cohort after adjustment for age, gender, and comorbidities.
  
  
  CONCLUSIONS
  Pneumococcal pneumonia is associated with an increased risk of lung cancer. Thus, physicians should remain aware of this association when assessing patients with pneumococcal pneumonia.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Te-Yu
authors.initials: TY
authors.lastname: Lin
authors.forename: Wen-Yen
authors.initials: WY
authors.lastname: Huang
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.forename: Fung-Chang
authors.initials: FC
authors.lastname: Sung
authors.forename: Chia-Hung
authors.initials: CH
authors.lastname: Kao
authors.forename: Jun-Jun
authors.initials: JJ
authors.lastname: Yeh
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult