title: Coffee drinking and colorectal cancer risk: an evaluation based on a systematic review and meta-analysis among the Japanese population.
abstract: OBJECTIVE
  It remains unclear whether coffee drinking is associated with colorectal cancer risk. We performed a systematic review and meta-analysis of epidemiologic studies on this issue among the Japanese population.
  
  
  METHODS
  Original data were obtained from MEDLINE searches using PubMed or from searches of the 'Ichushi' database, complemented with manual searches. Meta-analysis was performed by using the random effects model to estimate the summary relative risk with 95% confidence interval according to the study design. The final judgment was made based on a consensus of the research group members with consideration for both epidemiological evidence and biological plausibility.
  
  
  RESULTS
  We identified five cohort studies and nine case-control studies. Of these, one cohort study reported a strong inverse association (in women only), whereas three case-control studies reported a strong inverse association with colon or rectal cancer. In meta-analysis, high consumption of coffee was not appreciably associated with colorectal cancer risk among cohort studies, whereas it was associated with significantly lower risk of colorectal or colon cancer among case-control studies. The summary relative risk/odds ratio (95% confidence interval) for the highest versus lowest categories of coffee consumption was 0.95 (0.77-1.17) and 0.78 (0.65-0.95) for cohort and case-control studies, respectively.
  
  
  CONCLUSIONS
  The evidence is insufficient to support that coffee drinking increases or decreases the risk of colorectal cancer among the Japanese population.
authors.affiliation: Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo.
authors.forename: Shamima
authors.initials: S
authors.lastname: Akter
authors.affiliation: Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Kashino
authors.affiliation: Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo mizoue@ri.ncgm.go.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mizoue
authors.affiliation: Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Matsuo
authors.affiliation: Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, Nagoya.
authors.forename: Hidemi
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of Preventive Medicine, Nagoya University Graduate School of Medicine, Nagoya.
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.affiliation: Department of Epidemiology and Preventive Medicine, Gifu University Graduate School of Medicine, Gifu.
authors.forename: Chisato
authors.initials: C
authors.lastname: Nagata
authors.affiliation: Center for Cancer Control and Statistics, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka.
authors.forename: Tomio
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sadakane
authors.affiliation: Department of Preventive Medicine, Faculty of Medicine, Saga University, Saga.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, Sapporo.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.affiliation: Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Sugawara
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo.
authors.forename: Norie
authors.initials: N
authors.lastname: Sawada
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo AXA Department of Health and Human Security, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo.
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
mesh_terms: D016022:Case-Control Studies; D003069:Coffee / Q000737:chemistry* / Q000633:toxicity; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology; D016208:Databases, Factual; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016017:Odds Ratio; D012306:Risk
chemical_list: D003069:Coffee
keywords: Japanese; coffee; colorectal cancer; meta-analysis; systematic review