title: Meta-analysis of the association between cigarette smoking and incidence of Hodgkin's Lymphoma.
abstract: BACKGROUND
  Previous studies have suggested a relationship between smoking and Hodgkin's lymphoma (HL). The main objective of this study was to evaluate this potential association with a meta-analysis of observational studies.
  
  
  METHODS
  A literature search was undertaken through December 2010 looking for observational studies evaluating the association between smoking and HL. From 714 articles, 17 were included in this study. Outcome was calculated and reported as odds ratio (OR). Heterogeneity was assessed by using the I(2) index. Publication bias was evaluated by trim-and-fill analysis. Quality assessment was performed with the Newcastle-Ottawa scale.
  
  
  RESULTS
  Our analysis showed an OR of developing HL of 1.35 (95% CI, 1.17 to 1.56; P < .001) in current smokers. Former smokers did not have an increased risk of HL. In subset analyses of current smokers, men and older individuals had ORs of HL of 1.78 (95% CI, 1.46 to 2.17; P < .001) and 1.77 (95% CI, 1.23 to 2.54; P = .002), respectively. In addition, the OR of HL was increased in individuals who smoke more than 20 cigarettes per day, have smoked more than 20 years, or have smoked more than 15 pack-years at 1.51 (95% CI, 1.16 to 1.98; P = .002), 1.84 (95% CI, 1.47 to 2.32; P < .001), and 1.97 (1.53 to 2.54; P < .001), respectively. Meta-regression analyses showed a relative OR of HL of 1.007 (95% CI, 1.001 to 1.013; P = .025) per cigarette per day and of 1.013 (95% CI, 1.006 to 1.019; P < .001) per year of smoking.
  
  
  CONCLUSIONS
  Smoking seems to increase the odds of developing HL in current smokers. The risk of HL is higher in men and older individuals and increases with higher intensity and longer duration of smoking.
authors.affiliation: The Warren Alpert Medical School of Brown University and The Miriam Hospital, Providence, RI, USA. jcastillo@lifespan.org
authors.forename: Jorge J
authors.initials: JJ
authors.lastname: Castillo
authors.forename: Samir
authors.initials: S
authors.lastname: Dalia
authors.forename: Helen
authors.initials: H
authors.lastname: Shum
mesh_terms: D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006689:Hodgkin Disease / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D011159:Population Surveillance / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*