title: High serum iron is associated with increased cancer risk.
abstract: Epidemiologic studies linking high serum iron with cancer risks are limited and inconclusive, despite evidence implicating body iron in human carcinogenesis. A cohort of 309,443 adults in Taiwan who had no history of cancer had serum iron levels tested at the time of recruitment (1997-2008). Initially measured iron levels were associated with subsequent cancer risk by linking individuals with the National Cancer Registry and National Death File. HRs were calculated by the Cox model. One third of males (35%) and one fifth of females (18%) had high serum iron (≥120 μg/dL), which was associated with a 25% increase in risk for incidence of all cancers [HR, 1.25; 95% confidence interval (CI), 1.16-1.35] and with a 39% increase in risk for mortality from all cancers (HR, 1.39; 95% CI, 1.23-1.57). The relationship between serum iron and cancer risk was a J-shaped one, with higher cancer risk at both ends, either at lower than 60 μg/dL or higher than 120 μg/dL. At the higher end, cancer risk increased by 4% for every 10 μg/dL increment above 80 μg/dL, showing a dose-response relationship, with 60 to 79 μg/dL as a reference level. In a sensitivity analysis, the increases in risk were still observed after the first 5 years of cancer cases were excluded. Liver cancer risk was increased in HBV (-) non-hepatitis B carrier (3-fold) and HBV (+) hepatitis B carrier (24-fold). Lifestyle risks such as smoking, drinking, or inactivity interacted synergistically with high serum iron and significantly increased the cancer risks. The liver (HR, 2.49; 95% CI, 1.97-3.16) and the breast (HR, 1.31; 95% CI, 1.01-1.70) were the two major cancer sites where significant cancer risks were observed for serum iron either ≥120 μg/dL or ≥140 μg/dL, respectively. This study reveals that high serum iron is both a common disorder and a marker of increased risk for several cancers.
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan. China Medical University Hospital, Taichung, Taiwan. cwengood@nhri.org.tw.
authors.forename: Chi Pang
authors.initials: CP
authors.lastname: Wen
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: June Han
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Tai
authors.affiliation: Long Beach Veterans Administration Hospital, University of Irvine, California.
authors.forename: Christopher
authors.initials: C
authors.lastname: Wen
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Shiuan Be
authors.initials: SB
authors.lastname: Wu
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Min Kuang
authors.initials: MK
authors.lastname: Tsai
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan. Department of Environmental Toxicology, University of California, Davis.
authors.forename: Dennis P H
authors.initials: DP
authors.lastname: Hsieh
authors.affiliation: National Environmental Health Center, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Hung-Che
authors.initials: HC
authors.lastname: Chiang
authors.affiliation: Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Chao Agnes
authors.initials: CA
authors.lastname: Hsiung
authors.affiliation: Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
authors.forename: Chung Y
authors.initials: CY
authors.lastname: Hsu
authors.affiliation: Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
authors.forename: Xifeng
authors.initials: X
authors.lastname: Wu
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007501:Iron / Q000097:blood*; D008019:Life Style; D008297:Male; D009369:Neoplasms / Q000097:blood / Q000209:etiology*; D016016:Proportional Hazards Models; D012306:Risk
chemical_list: D007501:Iron