'Clinical Paradox'? Bariatric Surgery May Protect From GI Cancers

Megan Brooks

January 12, 2023

Bariatric surgery for severe obesity does not appear to raise the risk of esophageal and gastric cancer, a new study shows.

In fact, an analysis of close to 1 million French adults suggests that the weight-loss surgery may offer some protection against these cancers.

The study results present a "clinical paradox," according to authors of a commentary published this week along with the study in JAMA Surgery. A procedure known to increase the risk of gastroesophageal reflux disease (GERD), and potentially adenocarcinoma of the distal esophagus and gastroesophageal junction, may help shield patients from esophagogastric cancer.

The study marks "an important step toward improving the understanding of potential lifetime risks of bariatric surgery and overall major health benefits of surgically induced weight loss," commentary authors Piotr Gorecki, MD, and Michael Zenilman, MD, with Weill Cornell Medicine in New York City, write.

Recent data indicate that excess body weight is associated with nearly 8% of cancer cases and 6.5% of cancer deaths. Studies also show that bariatric surgery can reduce the risk of some cancers, but whether this extends to esophageal and gastric cancer remains unclear.

To investigate, the researchers used French national data to compare the incidence of esophageal and gastric cancer in 303,709 mostly female patients with obesity who underwent bariatric surgery and a matched group of 605,140 patients with obesity who did not undergo the surgery.

The mean age of the cohort was about 40 years. The mean period of follow-up was 6 years for the surgery group and 5.6 years for the control arm. A total of 337 patients underwent esophagogastric cancer — 83 in the surgical group and 254 in the control group. Gastric cancer was about two times more common than esophageal cancer (225 vs 112 patients).

The incidence rate of esophagogastric cancer was higher in the control group than in the surgery group — 6.9 vs 4.9 cases per 100,000 population per year, for an incidence rate ratio of 1.42 (P = .005).

Bariatric surgery was associated with a significant 24% lower risk of esophagogastric cancer (hazard ratio [HR], 0.76; P = .03) and a 40% lower risk of overall in-hospital mortality, defined as "any death occurring during a hospital stay regardless of the cause" (HR, 0.60; P < .001).

The authors also found no significant difference in cancer outcomes and type of bariatric procedure, which included sleeve gastrectomy, gastric bypass, and adjustable gastric banding.

Lazzati and colleagues note key study limitations include the retrospective design, limited follow-up period, and lack of histologic data on the specific cancers. In addition, the study population was relatively young, whereas esophageal cancer is more common in older people.

But overall, the findings suggest that bariatric surgery can be performed to treat severe obesity without increasing the risk of esophageal and gastric cancer, the authors conclude.

"It seems that the balance between protective factors (weight loss, metabolic effects, and eradication of H pylori infection) and risk factors (GERD and bile reflux) for cancer after bariatric surgery is in favor of protective factors," the authors, led by Andrea Lazzati, MD, PhD, of Centre Hospitalier Intercommunal de Créteil, France, explain.

Although the potential protective mechanisms remain unclear, in their commentary, Gorecki and Zenilman suggest that a reduction in chronic inflammation and immunosuppression following bariatric surgery could help explain the results.

Although the study provides "reassurance of the protective clinical benefits of weight loss surgery," more large-scale studies are needed to "better identify, elucidate, and address the pathophysiological processes of bariatric procedure," Gorecki and Zenilman conclude.

No specific funding for the study was reported. Lazzati has received personal fees from Johnson & Johnson, Medtronic, and Gore. Zenilman has received personal fees from Academic Medical Professionals Insurance and Mohamed & Obaid Almulla Group.

JAMA Surg. Published online January 11, 2023. Abstract, Editorial

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