title: Herpes zoster as a marker of occult cancer: A systematic review and meta-analysis.
abstract: Researchers have advocated for an increased awareness of occult cancer among herpes zoster patients, but there are no systematic reviews to support these claims. We therefore conducted a systematic review and meta-analysis of evidence on zoster and risk of occult cancer.
  
  
  
  Through February 18, 2016, we searched PubMed, EMBASE and references of relevant papers for studies on zoster and risk of any cancer. One author screened retrieved papers by title and abstract; included papers were reviewed by two authors for eligibility, data extraction, and potential biases. Despite statistical heterogeneity, associations were consistently in the same direction and we therefore computed pooled relative risks using random-effects models.
  
  
  
  We identified 46 eligible studies, 10 of which considered all cancer types combined. The pooled relative risk for any cancer was 1.42 (95% confidence interval: 1.18, 1.71) overall and 1.83 (95% confidence interval: 1.17, 2.87) at one year after zoster. Considering cancer subtypes, the highest estimates were generally reported for occult hematological cancer. The absolute risk of any cancer at one year after presentation with zoster was 0.7-1.8%.
  
  
  
  This study supports an association between zoster and occult cancer, but the low absolute risk of cancer limits the clinical implications.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: saj@clin.au.dk.
authors.forename: S A J
authors.initials: SA
authors.lastname: Schmidt
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Mor
authors.affiliation: Department of Clinical Microbiology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: H C
authors.initials: HC
authors.lastname: Schønheyder
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands; Department of Clinical Endocrinology and Metabolism, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: O M
authors.initials: OM
authors.lastname: Dekkers
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: D
authors.initials: D
authors.lastname: Cronin-Fenton
mesh_terms: D055088:Early Detection of Cancer; D006562:Herpes Zoster / Q000150:complications* / Q000453:epidemiology / Q000821:virology; D014645:Herpesvirus 3, Human / Q000302:isolation & purification; D006801:Humans; D009369:Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D012307:Risk Factors
keywords: Early detection of cancer; Epidemiology; Herpes zoster; Neoplasms