title: Contact with ruminants is associated with esophageal squamous cell carcinoma risk.
abstract: The etiology of esophageal squamous cell carcinoma (ESCC) in the high risk area of northern Iran is only partially known. We aimed to investigate prolonged animal contact as a risk factor for ESCC in this population. From 2003 to 2007, we administered a validated questionnaire to 300 ESCC cases and 571 randomly selected controls matched for neighborhood of residence, age (±2 years) and sex. Questions on lifelong exposure to equines, ruminants, canines, and poultry, including duration and level of contact, were asked in a face-to-face interviews. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) adjusted for potential confounders. A total of 94.7% of cases and 68.7% of controls reported lifelong history of contact with ruminants. After controlling for potential confounders, contact with ruminants was associated with an eightfold increase (95% CI: 3.92-14.86) in risk of ESCC, and increments in duration of contact raised the risk estimates in a dose-dependent manner. Contact with equines and poultry did not significantly change associated OR for ESCC risk and contact with ruminants. OR (95% CI) for contact with canines was 1.99 (1.35-2.93) which after exclusion of contact with ruminants was not significant (OR for contact only with canine: 3.18, 95% CI: 0.73-13.17). These results add to the evidence that contact with ruminants may increase the risk of ESCC.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, 17177, Sweden; Digestive Oncology Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Dariush
authors.initials: D
authors.lastname: Nasrollahzadeh
authors.forename: Weimin
authors.initials: W
authors.lastname: Ye
authors.forename: Ramin
authors.initials: R
authors.lastname: Shakeri
authors.forename: Masoud
authors.initials: M
authors.lastname: Sotoudeh
authors.forename: Shahin
authors.initials: S
authors.lastname: Merat
authors.forename: Farin
authors.initials: F
authors.lastname: Kamangar
authors.forename: Christian C
authors.initials: CC
authors.lastname: Abnet
authors.forename: Farhad
authors.initials: F
authors.lastname: Islami
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.forename: Sanford M
authors.initials: SM
authors.lastname: Dawsey
authors.forename: Paul
authors.initials: P
authors.lastname: Brennan
authors.forename: Reza
authors.initials: R
authors.lastname: Malekzadeh
mesh_terms: D000368:Aged; D000822:Animal Husbandry; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000209:etiology*; D004781:Environmental Exposure / Q000009:adverse effects*; D004938:Esophageal Neoplasms / Q000209:etiology*; D000077277:Esophageal Squamous Cell Carcinoma; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D012418:Ruminants
keywords: animal contact; esophageal neoplasm; relative risk; risk factors; ruminants
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