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BOMSS 2014 Meeting Report

MGB results in weight-loss but linked to cancer

Mini-gastric bypass is safe early outcomes show
Procedure generates reflux of bile which is implicated in both gastric and oesophageal carcinogenesis

Early results of mini-gastric bypass show that the procedure is safe and effective however, researchers have highlighted concerns that the benefits of the procedure could negated by a long term risk of developing oesophago-gastric cancer. The topic was discussed at this year’s Annual Scientific Meeting of the British Obesity and Metabolic Surgery Society in Leamington Spa, UK, from 22 – 24 January.

According to Maureen Boyle from the Bariatric Unit, Sunderland Royal Hospital, Sunderland, UK, the early results from a single centre study suggest that mini gastric bypass is safe with acceptable complication rate and is effective as it is associated with good % weight loss.

Maureen Boyle

They analysed their prospective database to determine early results from mini-gastric bypass procedure in terms of complications, readmissions, weight loss and comorbidity resolution.

Between October 2012 and October 2013, there were a total of 40 mini-gastric bypass procedures, with all operations performed using a standardised laparoscopic approach with formation of a long lesser curve based gastric pouch and a gastroenterostomy at 2.0 meters from duodeno-jejunal flexure.

Twenty nine (72.5%) of these patients were females and the mean age was 41 years. The average weight and BMI of patients was 127kg (BMI 44.3). Preoperative conditions included ten (25%) patients who had type II diabetes mellitus and 15 patients (37.5%) who had hypertension. Two (5%) patients had a prior gastric balloon insertion and all patients were discharged on second postoperative day, following appropriate dietetic advice.

Boyle said that there were no early complication or mortality in this series, although there were two (5%) late (>30 days) readmissions.  The first patient was readmitted with vomiting at three months and diagnosed to have a marginal ulcer on endoscopy. They were treated with Lansoprazole and Sucralfate and the ulcer was healed on a subsequent endoscopic examination.  A second patient was readmitted five weeks after surgery with unexplained vomiting that lasted a short period and was presumed to be a viral infection.

She reported that excess weight loss was 67.4% at six months (n=14) and 89.7% at 12 (n=4) months, with all diabetic and hypertensive patients reporting a reduction in their medication.

To the researchers’ knowledge, this is the first mini gastric bypass series in the UK to report from any unit within the National Health Service.

Co-authors of this study were Neil Jennings, Kamal Mahawar, Shlok Balupuri and Peter K Small.

Cancer risk

In a second presentation, Dr John Bennett from the Cambridge Oesophago-gastric centre, Cambridge, UK, said that the benefits of reduced peri-operative complications in mini-gastric bypass may be outweighed by the long-term risk of developing oesophago-gastric cancer and given the likely risk of malignancy, mini-gastric bypass should not be offered to young patients seeking weight loss surgery.

Dr John Bennett

He outlined that mini-gastric bypass has been shown to achieve weight loss comparable to RYGB, but with fewer early complications. However, the procedure generates continuous reflux of bile into the gastric pouch and this bile reflux is implicated in both gastric and oesophageal carcinogenesis, increasing the risk of oesophago-gastric cancer in this patient group.

As a result, Bennett and colleagues conducted a literature review using the terms “minigastric bypass”, “gastric remnant cancer”, “oesophageal cancer”, “bile reflux and gastric/ oesophageal cancer”.

They found over 5,000 mini-gastric bypass cases up-to 2013 (age range 14-72 years) and report that significantly higher concentrations of bile salts were recorded in the gastric remnant of patients undergoing loop gastro-jejunostomy for gastric bypass as opposed to RYGB.

Furthermore, animal models of Barrett’s oesophagus and oesophageal adenocarcinoma have developed surgically generated entero-oesophageal reflux to induce carcinogenesis. In humans, population based studies show a significant increase in the relative risk of developing OGC in patients 20 years after Billroth II reconstruction for benign ulcer disease (RR 3.7).

“There is substantial evidence from in vitro and ex vivo models indicating a pro-mutagenic effect of bile salts in the upper GI tract,” said Bennett. “Combined acid and bile reflux increases this effect and is associated with oncogene expression modulation.”

He added that symptomatic bile reflux in mini-gastric bypass necessitates revision to RYGB reconstruction, although the long-term results relating to the effect of constant, sub-clinical reflux are not available.

Co-authors of this study were Richard H Hardwick, Peter Safranek, Vijayendran Sujendran and Andrew Hindmarsh.

Clinical commment: MGB cancer link: the evidence is very weak

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