title: Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions.
abstract: BACKGROUND
  The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.
  
  
  OBJECTIVE
  We performed meta-analyses of occupational cohort studies for five different lymphoma categories: Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), multiple myeloma (MM), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).
  
  
  METHODS
  We assessed three study quality dimensions to evaluate the impact of study quality variations on meta-relative risks (mRRs): stratification by the year of start of follow-up, stratification by the strength of the reported acute myelogenous leukemia association, and stratification by the quality of benzene exposure assessment.
  
  
  RESULTS
  mRRs for MM, ALL, and CLL increased with increasing study quality, regardless of the study quality dimension. mRRs for NHL also increased with increasing study quality, although this effect was less pronounced. We observed no association between occupational benzene exposure and HL.
  
  
  CONCLUSIONS
  Our meta-analysis provides support for an association between occupational benzene exposure and risk of MM, ALL, and CLL. The evidence for an association with NHL is less clear, but this is likely complicated by the etiologic heterogeneity of this group of diseases. Further consideration of the association between benzene and NHL will require delineation of risks by NHL subtype.
authors.affiliation: Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands.
authors.forename: Jelle
authors.initials: J
authors.lastname: Vlaanderen
authors.forename: Qing
authors.initials: Q
authors.lastname: Lan
authors.forename: Hans
authors.initials: H
authors.lastname: Kromhout
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Rothman
authors.forename: Roel
authors.initials: R
authors.lastname: Vermeulen
mesh_terms: D001554:Benzene; D006689:Hodgkin Disease / Q000139:chemically induced*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000139:chemically induced*; D015470:Leukemia, Myeloid, Acute / Q000139:chemically induced*; D008228:Lymphoma, Non-Hodgkin / Q000139:chemically induced*; D009101:Multiple Myeloma / Q000139:chemically induced*; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors
chemical_list: D001554:Benzene