Gastroesophageal reflux does not alter effects of body mass index on risk of esophageal adenocarcinoma.
OBJECTIVE
A history of high body mass index (BMI) is associated strongly with a risk of esophageal adenocarcinoma (EAC). We investigated whether gastroesophageal reflux is involved in this association.


METHODS
We analyzed data from a population-based Swedish nationwide study of patients with a new diagnosis of EAC (n = 189) or gastroesophageal junction adenocarcinoma (n = 262), and matched controls (n = 816), from 1995 through 1997. Our analysis included data on BMI 20 years before study inclusion; maximum adult BMI; frequency, severity, and duration of gastroesophageal reflux symptoms; tumor features; and covariates (sex, age, smoking, alcohol, fruit and vegetable intake, and socioeconomic status). We conducted stratified analyses and synergy tests, adjusting for covariates.


RESULTS
Odds ratios (ORs) for EAC among subjects with a BMI of 25 or higher 20 years before inclusion, compared with those with a BMI less than 25, did not differ significantly, without or with adjustment for gastroesophageal reflux frequency (OR, 3.1; 95% confidence interval [CI], 2.2-4.4; and OR, 3.3; 95% CI, 2.2-4.8, respectively), severity (OR, 3.3; 95% CI, 2.2-4.8), or duration (OR, 3.2; 95% CI, 2.2-4.7). However, there were interactions between BMI and categories of gastroesophageal reflux. BMI appeared to have the largest effect on gastroesophageal reflux frequency (synergy index, 8.9; 95% CI, 2.3-34.1 for maximum BMI; and gastroesophageal reflux >3 times/wk).


CONCLUSIONS
Based on a population-based study, the association between BMI and EAC does not appear to be affected by symptomatic gastroesophageal reflux, although there appears to be synergy between BMI and reflux.
Unit of Upper Gastrointestinal Research, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Division of Cancer Studies, King's College London, London, United Kingdom. Electronic address: jesper.lagergren@ki.se.
Jesper
J
Lagergren
Unit of Upper Gastrointestinal Research, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
Fredrik
F
Mattsson
Department of Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Olof
O
Nyrén
D000230:Adenocarcinoma / Q000453:epidemiology*; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D004938:Esophageal Neoplasms / Q000453:epidemiology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D018570:Risk Assessment; D013548:Sweden / Q000453:epidemiology
BMI; CI; Cancer Risk; EAC; GERD; JAC; OR; Obesity; Overweight; S; body mass index; confidence interval; esophageal adenocarcinoma; gastroesophageal junctional adenocarcinoma; odds ratio; synergy