title: Smoking, alcohol and family history of cancer as risk factors for small intestinal neuroendocrine tumors: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Risk factors for small intestinal neuroendocrine tumors (SI-NETs) are not well understood. The aim of this systematic literature review was to identify risk factors for SI-NET and to further assess these by meta-analysis.
  
  
  METHODS
  PubMed and abstracts from the ENETS and NANETS were searched for studies published until May 2015. Eligible studies were selected according to the PRISMA statement.
  
  
  RESULTS
  Seven studies evaluating six individual populations were included (study accrual period 1980-2012) in the meta-analysis, involving 765 (range 17-325) cases and 502,282 (range 52-498,376) controls. All studies were case-control by design. The following risk factors were reported in ≥2 studies: family history of any cancer, family history of colorectal cancer, ever alcohol use and ever smoking. The pooled OR was 1.34 (95% CI: 1.12-1.60; p < .01; I2= 0.0%) for family history of any cancer, 1.43 (95% CI: 1.15-1.79; p < .01; I2= 0.0%) for family history of colorectal cancer, 1.04 (95% CI: 0.63-1.72; p = .87; I2= 65.0%) for ever alcohol use and 1.40 (95% CI: 1.06-1.86; p < .05; I2= 49.3%) for ever smoking.
  
  
  CONCLUSIONS
  Family history of any cancer, family history of colorectal cancer and history of ever smoking were associated with an increased risk of SI-NET by meta-analysis. Alcohol consumption was not a significant risk factor for SI-NET. However, the studies reporting smoking and alcohol had a high degree of heterogeneity. Therefore, further studies are needed for clarification of smoking and alcohol as risk factors for the occurrence of SI-NET.
authors.affiliation: a Department of Hepato-Pancreato-Biliary Surgery , Oslo University Hospital , Oslo , Norway.|b Department of Surgery , Drammen Hospital, Vestre Viken Hospital Trust , Drammen , Norway.
authors.forename: Sven-Petter
authors.initials: SP
authors.lastname: Haugvik
authors.affiliation: c Institute of Clinical Medicine, University of Oslo , Oslo , Norway.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Basim Ibrahim
authors.affiliation: d Unit of Gastroenterology, Department of Medicine , Sahlgrenska University Hospital , Gothenburg , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Hedenström
authors.affiliation: e Digestive and Liver Disease Unit , II Medical School, University 'La Sapienza', S. Andrea Hospital , Rome , Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Valente
authors.affiliation: f Department of General Surgery , Royal Infirmary of Edinburgh , Edinburgh , Scotland.
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Hayes
authors.affiliation: g Department of Gastroenterology , University Medical Centre Ljubljana , Ljubljana , Slovenia.
authors.forename: Darko
authors.initials: D
authors.lastname: Siuka
authors.affiliation: a Department of Hepato-Pancreato-Biliary Surgery , Oslo University Hospital , Oslo , Norway.|c Institute of Clinical Medicine, University of Oslo , Oslo , Norway.
authors.forename: Ivar Prydz
authors.initials: IP
authors.lastname: Gladhaug
authors.affiliation: e Digestive and Liver Disease Unit , II Medical School, University 'La Sapienza', S. Andrea Hospital , Rome , Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Capurso
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects*; D005192:Family Health; D006801:Humans; D007414:Intestinal Neoplasms / Q000453:epidemiology* / Q000235:genetics; D008487:Medical History Taking; D018358:Neuroendocrine Tumors / Q000453:epidemiology* / Q000235:genetics; D010375:Pedigree; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*
keywords: NET; SI-NET; epidemiology; meta-analysis; risk factor; small intestinal neuroendocrine tumor