"The groundwork of all happiness is health." - Leigh Hunt

Weight loss surgery could halve cancer risk over time

May 1, 2023 — Weight-loss surgery has long been known to offer health advantages beyond actual weight reduction. Research has shown that diabetes can go into remission, sleep apnea can improve, and blood pressure can drop. Now researchers are adding a lower risk of cancer to the list.

The researchers compared nearly 56,000 individuals with obesity who had bariatric surgery with the identical number of people that didn't. They tracked how many individuals developed cancer over the subsequent decade.

There were lower than half as many cancer cases within the surgery group.

“We found a difference in the rates of breast cancer, colon cancer, liver cancer and ovarian cancer … with patients in the bariatric surgery group having a lower rate of these four cancers compared with the non-surgical control group,” said Vibhu Chittajallu, MD, lead study writer and a gastroenterologist at University Hospitals in Cleveland.

Obesity is linked to quite a few serious diseases, including type 2 diabetes, heart disease and cancer. The obesity epidemic is “one of the most serious health challenges in the United States today,” Chittajallu said during a media preview of research highlights for Digestive Disease Week 2023 on April 27.

Obesity can be widespread. The CDC reports that nearly 42% of American adults suffer from obesity and the rates proceed to rise.

Chittajallu and his colleagues identified 55,789 individuals with obesity who had undergone the surgery, in addition to a control group of others who had not undergone the surgery, using billing codes in a national database. Their retrospective observational study included individuals who had undergone sleeve gastrectomy, gastric bypass or gastric banding at certainly one of 47 health organizations across the country.

Key findings

They found that 4% of patients who underwent surgery and eight.9% of those that didn't develop cancer. There were fewer recent cases of several forms of cancer within the bariatric surgery group.

Cancer development over 10 years

The researchers found significant reductions in 4 specific cancers linked to obesity: breast cancer, colon cancer, liver cancer and ovarian cancer. There were no significant differences between the groups for several other cancers, including kidney cancer, rectal cancer and endometrial cancer.

Why the danger of cancer decreases after bariatric surgery will not be yet fully understood, says Chittajallu. However, bariatric surgery has been shown to scale back excessive inflammation, increase insulin levels and regulate hormone levels.

Cancer type # Cases after surgery # Cases without surgery
Breast 501 751
colon 201 360
liver 969 2,198
pancreas 54 86
Ovary 130 214
thyroid 154 175

“Makes logical sense”

Loren Laine, MD, moderator of the press conference, called the study “fascinating.”

“Obesity is clearly associated with a number of different cancers, and that's very important, so it makes sense that if you lose weight, you'll reduce that risk,” said Laine, a professor of drugs and chief of the division of digestive health at Yale University School of Medicine in New Haven, Connecticut.

The researchers controlled for risk aspects that might also contribute to cancer development, including smoking habits, alcohol consumption, heart disease and hormone therapies. Laine added that the researchers likely couldn't control for all aspects because they were limited to the data available within the database.

Unanswered questions

If future research shows that the more weight you lose, the upper your risk of cancer, “that would be fascinating,” Laine said. It would even be interesting to know whether other approaches, resembling weight-loss drugs, could also reduce cancer rates.

“We need to do more research to understand how bariatric surgery affects cancer risk,” Chittajallu said, “but the significant results of this study suggest this is an exciting avenue for further study.”