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MGB cancer link: the evidence is very weak

On 11 February 2014, Bariatricnews.net published an article featuring a paper by Maureen Boyle and co-workers at Sunderland Royal Hospital who reported an analysis of a small prospective database on the mini-gastric bypass (MGB); this first MGB series from the UK found excellent safety and weight loss compared to other bariatric operations, as found recently in large series (1-3).

However, an additional presentation by Bennett et al from Cambridge stated that the reduced peri-operative complications in the MGB may be outweighed by the long-term risk of developing oesophago-gastric cancer.  This is a theoretical study. A SurveyMonkey questionnaire filled out before and reported at the Paris Consensus Conference on MGB in October 2013, involving 16,651 MGBs performed by the expert attendees over the past 16 years found no development of carcinoma in the gastric channel or oesophagus (4).  As an aside, the MGB has been effective in resolving GE reflux disease, likely related to traction which the gastro-jejunal anastomosis provides on the gastric pouch, which reduces the cardia within the abdomen, plus resolution of the patient’s obesity.

Increased concentration of bile could be problematic in operations which result in bile at the cardia – high Billroth II gastrectomy and the old Mason loop horizontal gastric bypass. In the 1960s and 70s, we performed 1,000s of vagotomies and pyloroplasties when duodenal ulcer was common, and all had bile in the lower end of their stomach, but none developed carcinoma. The Billroth II gastrectomy and old Mason loop gastric bypass are definitely not the MGB, which has a long vertical pouch to at least the crow’s foot. Furthermore, long-term studies following Billroth II did not find increase in cancer in the remaining stomach, although the likely presence of H. pylori was then unknown and untreated (5-8).

Studies with concentrated bile have been performed in the rodent stomach, in which the proximal two-thirds is squamous cell and the distal one-third is glandular.  It was shown in 1991 that concentrated bile or irritants in the rat’s stomach led to hyperplasia and malignancy in the proximal two-thirds on the unique rat stomach (which is squamous cell) and not in the glandular distal one-third (which corresponds to the human stomach) (9). This should cause some concern in another bariatric operation, the sleeve gastrectomy, where GE reflux is not infrequent.

About 40 carcinomas have been reported after Roux-Y gastric bypass, gastric banding and lately sleeve gastrectomy. No doubt someday a carcinoma may also be reported in the gastro-oesophageal tube after MGB, but the evidence for increased concern is very weak.

References

  1. Lee WJ, Ser KH, Lee YC, et al. Laparoscopic Roux-en-Y vs. mini-gastric bypass for the treatment of morbid obesity: a 10-year experience. Obes Surg 2012;22:1827-34.
  2. Musella M, Sousa A, Greco F, et al. The laparoscopic mini-gastric bypass: the Italian experience: outcomes from 974 consecutive cases in a multi-center review. Surg Endosc 2014;28:156-63.
  3. Milone M, Di Minno MN, Leongito M, et al. Bariatric surgery and diabetes remission: sleeve gastrectomy or mini-gastric bypass? World J Gastroenterol 2013;19:6590-7.
  4. Deitel M. Mini-gastric (one-anastomosis) bypass becoming a mainstream operation. Bariatric News, issue 18, Dec. 2013 – page 13.
  5. Schafer LW, Larson DE, Melton III LJ. The risk of gastric carcinoma after surgical treatment for benign ulcer disease: a population-based study in Olmsted County, MN. N Engl J Med 1983;309:1210-3.
  6. Clark CG, Fresni A, Gledhill T. Cancer following gastric surgery. Br J Surg 1985;72:591-4.
  7. Luukkonen P, Kalima T, Kivilaako E. Decreased risk of gastric stump carcinoma after partial gastrectomy. Hepatogastroenterol 1990;37:392-4.
  8. Bassily R, Smallwood RA, Crotty R. Risk of gastric cancer is not increased after partial gastrectomy.  J Gastroenterol Hepatol 2000;15:762-5.
  9. Frantz JD, Bretton G, Cartwright ME, et al. Proliferative lesions of the non-glandular and glandular stomach of rats. In: Guides for Toxicologic Pathology STP/ARF/AFIP, Washington, DC, 1991.