title: Research recommendations for selected IARC-classified agents.
abstract: OBJECTIVE
  There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans.
  
  
  METHODS
  For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent.
  
  
  METHODS
  Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches.
  
  
  RESULTS
  Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation.
  
  
  CONCLUSIONS
  Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.
authors.affiliation: Epidemiology and Surveillance Research, American Cancer Society, Atlanta Georgia 30303, USA. elizabeth.ward@cancer.org
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Ward
authors.forename: Paul A
authors.initials: PA
authors.lastname: Schulte
authors.forename: Kurt
authors.initials: K
authors.lastname: Straif
authors.forename: Nancy B
authors.initials: NB
authors.lastname: Hopf
authors.forename: Jane C
authors.initials: JC
authors.lastname: Caldwell
authors.forename: Tania
authors.initials: T
authors.lastname: Carreón
authors.forename: David M
authors.initials: DM
authors.lastname: DeMarini
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Fowler
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Goldstein
authors.forename: Kari
authors.initials: K
authors.lastname: Hemminki
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Hines
authors.forename: Kirsti Husgafvel
authors.initials: KH
authors.lastname: Pursiainen
authors.forename: Eileen
authors.initials: E
authors.lastname: Kuempel
authors.forename: Joellen
authors.initials: J
authors.lastname: Lewtas
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Lunn
authors.forename: Elsebeth
authors.initials: E
authors.lastname: Lynge
authors.forename: Damien M
authors.initials: DM
authors.lastname: McElvenny
authors.forename: Hartwig
authors.initials: H
authors.lastname: Muhle
authors.forename: Tamie
authors.initials: T
authors.lastname: Nakajima
authors.forename: Larry W
authors.initials: LW
authors.lastname: Robertson
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Rothman
authors.forename: Avima M
authors.initials: AM
authors.lastname: Ruder
authors.forename: Mary K
authors.initials: MK
authors.lastname: Schubauer-Berigan
authors.forename: Jack
authors.initials: J
authors.lastname: Siemiatycki
authors.forename: Debra
authors.initials: D
authors.lastname: Silverman
authors.forename: Martyn T
authors.initials: MT
authors.lastname: Smith
authors.forename: Tom
authors.initials: T
authors.lastname: Sorahan
authors.forename: Kyle
authors.initials: K
authors.lastname: Steenland
authors.forename: Richard G
authors.initials: RG
authors.lastname: Stevens
authors.forename: Paolo
authors.initials: P
authors.lastname: Vineis
authors.forename: Shelia Hoar
authors.initials: SH
authors.lastname: Zahm
authors.forename: Lauren
authors.initials: L
authors.lastname: Zeise
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Cogliano
mesh_terms: D000818:Animals; D015197:Carcinogenicity Tests; D019317:Evidence-Based Medicine; D006801:Humans