title: Cigarette smoking and risk of non-Hodgkin lymphoma: a pooled analysis from the International Lymphoma Epidemiology Consortium (interlymph).
abstract: BACKGROUND
  The International Lymphoma Epidemiology Consortium (InterLymph) provides an opportunity to analyze the relationship between cigarette smoking and non-Hodgkin lymphoma with sufficient statistical power to consider non-Hodgkin lymphoma subtype. The results from previous studies of this relationship have been inconsistent, likely due to the small sample sizes that arose from stratification by disease subtype. To clarify the role of cigarette smoking in the etiology of non-Hodgkin lymphoma, we conducted a pooled analysis of original patient data from nine case-control studies of non-Hodgkin lymphoma conducted in the United States, Europe, and Australia.
  
  
  METHODS
  Original data were obtained from each study and uniformly coded. Risk estimates from fixed-effects and two-stage random-effects models were compared to determine the impact of interstudy heterogeneity. Odds ratios (OR) and 95% confidence intervals (95% CI) were derived from unconditional logistic regression models, controlling for study center, age, sex, and race.
  
  
  RESULTS
  In our pooled study population of 6,594 cases and 8,892 controls, smoking was associated with slightly increased risk estimates (OR, 1.07; 95% CI, 1.00-1.15). Stratification by non-Hodgkin lymphoma subtype revealed that the most consistent association between cigarette smoking and non-Hodgkin lymphoma was observed among follicular lymphomas (n = 1452). Compared with nonsmokers, current smokers had a higher OR for follicular lymphoma (1.31; 95% CI, 1.12-1.52) than former smokers (1.06; 95% CI, 0.93-1.22). Current heavy smoking (> or = 36 pack-years) was associated with a 45% increased OR for follicular lymphoma (1.45; 95% CI, 1.15-1.82) compared with nonsmokers.
  
  
  CONCLUSIONS
  Cigarette smoking may increase the risk of developing follicular lymphoma but does not seem to affect risk of the other non-Hodgkin lymphoma subtypes we examined. Future research is needed to determine the biological mechanism responsible for our subtype-specific results.
authors.affiliation: Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Conneticut, USA. mortonli@mail.nih.gov
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Morton
authors.forename: Patricia
authors.initials: P
authors.lastname: Hartge
authors.forename: Theodore R
authors.initials: TR
authors.lastname: Holford
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Holly
authors.forename: Brian C H
authors.initials: BC
authors.lastname: Chiu
authors.forename: Paolo
authors.initials: P
authors.lastname: Vineis
authors.forename: Emanuele
authors.initials: E
authors.lastname: Stagnaro
authors.forename: Eleanor V
authors.initials: EV
authors.lastname: Willett
authors.forename: Silvia
authors.initials: S
authors.lastname: Franceschi
authors.forename: Carlo
authors.initials: C
authors.lastname: La Vecchia
authors.forename: Ann Maree
authors.initials: AM
authors.lastname: Hughes
authors.forename: Wendy
authors.initials: W
authors.lastname: Cozen
authors.forename: Scott
authors.initials: S
authors.lastname: Davis
authors.forename: Richard K
authors.initials: RK
authors.lastname: Severson
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Susan T
authors.initials: ST
authors.lastname: Mayne
authors.forename: Fred R
authors.initials: FR
authors.lastname: Dee
authors.forename: James R
authors.initials: JR
authors.lastname: Cerhan
authors.forename: Tongzhang
authors.initials: T
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004812:Epidemiologic Methods; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000145:classification / Q000453:epidemiology / Q000209:etiology*; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*