Bariatric Surgery May Cut Cancer in Obesity With Liver Disease

In a large cohort of insured working adults with severe obesity and nonalcoholic fatty liver disease (NAFLD), among those who underwent bariatric surgery, the rate of incident cancer was lower during a 10-month median follow-up period. The rate was especially lower with regard to obesity-related cancers. The risk reduction was greater among patients with cirrhosis.

Among almost 100,000 patients with severe obesity (body mass index >40 kg/m2) and NAFLD, those who underwent bariatric surgery had an 18% and 35% lower risk of developing any cancer or obesity-related cancer, respectively.

Bariatric surgery was associated with a significantly lower risk of being diagnosed with colorectal, pancreatic, endometrial, and thyroid cancer, as well as hepatocellular carcinoma and multiple myeloma (all obesity-related cancers). The findings are from an observational study by Vinod K. Rustgi, MD, MBA, and colleagues, which was published online March 17 in Gastroenterology.

It was not surprising that bariatric surgery is effective in reducing the malignancy rate among patients with cirrhosis, the researchers write, because the surgery results in long-term weight loss, resolution of nonalcoholic steatohepatitis (NASH), and regression of fibrosis.

“Cirrhosis can happen from fatty liver disease or NASH,” Rustgi, a hepatologist at Rutgers Robert Wood Johnson School of Medicine, New Brunswick, New Jersey, explained to Medscape Medical News.

“It’s becoming the fastest growing indication for liver transplant, but also the reason for increased rates of hepatocellular carcinoma,” he said.

Current treatment for patients with obesity and fatty liver disease begins with lifestyle changes to lose weight, he continued. “As people lose 10% of their weight, they actually start to see regression of fibrosis in the liver that is correlated with [lower rates of] malignancy outcomes and other deleterious outcomes,” he said. But long-lasting weight loss is extremely difficult to achieve.

Future studies “may identify new targets and treatments, such as antidiabetic-, satiety-, or GLP-1-based medications, for chemoprevention in NAFLD/NASH,” the investigators suggest. However, pharmaceutical agents will likely be very expensive when they eventually get marketed, Rustgi observed.

Although “bariatric surgery is a more aggressive approach than lifestyle modifications, surgery may provide additional benefits, such as improved quality of life and decreased long-term healthcare costs,” he and his coauthors conclude.

Rising Rates of Fatty Liver Disease, Obesity

An estimated 30% of the population of the United States has NAFLD, the most common chronic liver disease, the researchers note in their article. The prevalence of NAFLD increased 2.8-fold in the United States between 2003 and 2011, in parallel with increasing obesity.

NAFLD is more common among male patients with obesity and diabetes and Hispanic patients; “70% of [patients with diabetes] may have fatty liver disease, according to certain surveys,” Rustgi noted.

Cancer is the second greatest cause of mortality among patients with obesity and NAFLD, he continued, after cardiovascular disease. Cancer mortality is higher than mortality from liver disease.

Obesity-related cancers include adenocarcinoma of the esophagus, cancers of the breast (in postmenopausal women), colon, rectum, endometrium (corpus uterus), gallbladder, gastric cardia, kidney (renal cell), liver, ovary, pancreas, and thyroid, as well as meningioma and multiple myeloma, according to a 2016 report from the International Agency for Research on Cancer working group.

Obesity-related cancer accounted for 40% of all cancer in the United States in 2014 — 55% of cancers in women, and 24% of cancers in men, according to a study published in Morbidity and Mortality Weekly Report in 2017, as previously reported by Medscape Medical News.

Several studies, including one presented at Obesity Week in 2019 and later published, have shown that bariatric surgery is linked with a lower risk for cancer in general populations.

One meta-analysis reported that NAFLD is an independent risk factor for cholangiocarcinoma and colorectal, breast, gastric, pancreatic, prostate, and esophageal cancers. In another study, NAFLD was associated with a twofold increased risk for hepatocellular carcinoma and uterine, stomach, pancreatic, and colon cancers, Rustgi and colleagues note.

Until now, the impact of bariatric surgery on the risk for cancer among patients with obesity and NAFLD was unknown.

Does Bariatric Surgery Curb Cancer Risk in Liver Disease?

The researchers examined insurance claims data from the national MarketScan database from January 1, 2007, to December 31, 2017, for patients aged 18 to 64 years who had health insurance from 350 employers and 100 insurers.

They identified 98,090 patients with severe obesity who were newly diagnosed with NAFLD during the period 2008 to 2017.

Roughly a third of the cohort (33,435 patients) underwent bariatric surgery.

From 2008 to 2017, laparoscopic sleeve gastrectomies increased from 4% of bariatric procedures to 68% of all surgeries. Laparoscopic adjustable gastric band and laparoscopic Roux-en-Y gastric bypass procedures fell from 35% to <1% and from 49% to 28%, respectively.

Patients who underwent bariatric surgery were younger (mean age, 44 vs 46 years), were more likely to be women (74% vs 62%), and were less likely to have a history of smoking (6% vs 10%).

During a mean follow-up of 22 months (and a median follow-up of 10 months), there were 911 incident cases of obesity-related cancers. These included cancer of the colon (116 cases), rectum (15), breast (in postmenopausal women; 131), kidney (120), esophagus (16), gastric cardia (8), gallbladder (4), pancreas (44), ovaries (74), endometrium (135), and thyroid (143), as well as hepatocellular carcinoma (49), multiple myeloma (50), and meningioma (6). There were 1912 incident cases of other cancers, such as brain and lung cancers and leukemia.

A total of 258 patients who underwent bariatric surgery developed an obesity-related cancer (an incidence of 3.83 per 1000 person-years), compared with 653 patients who did not have bariatric surgery (an incidence of 5.63 per 1000 person-years).

The researchers note that study limitations include the fact that it was restricted to privately insured individuals aged 18 to 64 years with severe obesity. In addition, “the short median follow-up may underestimate the full effect of bariatric surgery on cancer risk,” they write.

The authors have disclosed no relevant financial relationships.

Gastroenterology. Published online March 17, 2021. Full text

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