Risk of gastric cancer after Roux-en-Y gastric bypass

Objective: To evaluate the risk of gastric cancer after Roux-en-Y gastric bypass (RYGB). Design: Rats randomly underwent 1 of the following: RYGB, duodenojejunal bypass (DJB), or a sham operation. Postoperatively, rats underwent a protocol of cancer induction by means of both continuous (200 ppm in tap water for 16 weeks) and intermittent (50-mg/kg intraesophageal injection, once a week, for 12 weeks) administration of N-methyl-N-nitrosourea. Setting: Institut de Recherche Contre les Canceurs de l'Appareil Digestif-European Institute of Telesurgery. Study Animals: Fifty-five Fischer 344 rats. Main Outcome Measures: Seventeen weeks after the operation, we performed a pathologic examination of the whole stomach in all animals to assess for the presence of cancer and/or premalignant lesions. Bilirubin concentration,gastric bacterial flora, and any other pathologic findings were also recorded. Results: In rats in the sham and DJB groups, the incidence of gastric cancer was 85% and 75%, respectively (P = .63), whereas only 23% of rats in the RYGB group developed gastric cancer (4-fold reduction; P = .002). The remnant stomach of rats in the RYGB group also showed a lower bilirubin concentration(P < .01) and a lower bacterial count (P < .05) compared with both the DJB and sham groups. Conclusions: This study shows that RYGB reduces the risk of gastric cancer in an experimental model of dietary-induced carcinogenesis. Lack of direct contact with carcinogens, lower bile reflux, and a lower bacteria concentration in the gastric content may be responsible for these observations. These data suggest that RYGB may be a safe option for the treatment of morbid obesity even in areas with high gastric cancer incidence.