May 1, 2023 — Weight loss surgery has long been known to provide health benefits beyond the actual pounds lost. Diabetes can go into remission, sleep apnea can improve, and blood pressure can decrease, research has shown. Now researchers are adding a lower risk of cancer to the list.
The researchers compared almost 56,000 people with obesity who had bariatric surgery to the same number who did not. They tracked how many people developed cancer over the next 10 years.
The surgery group had less than half as many cases of cancer.
“We did see a difference in breast cancer, colon cancer, liver cancer, and ovarian cancer incidence … with patients in the bariatric surgery group having lower incidence of these four types of cancers when compared to the non-surgical control group,” said Vibhu Chittajallu, MD, lead study author and a gastroenterology fellow at University Hospitals in Cleveland.
Obesity has been associated with multiple serious illnesses, including type 2 diabetes, heart disease, and cancer. The obesity epidemic is “one of the most serious health challenges in the U.S. today,” Chittajallu said during an April 27 media preview of research highlights for Digestive Disease Week 2023.
Obesity is also common. The CDC reports that nearly 42% of American adults have obesity, and rates continue to rise.
Chittajallu and colleagues identified 55,789 people with obesity who underwent the surgery and a control group of others who did not by using billing codes in a national database. Their retrospective, observational study included people undergoing sleeve gastrectomy, gastric bypass, and gastric band procedures at one of 47 health care organizations nationwide.
Key Findings
They found 4% of the surgery group and 8.9% of the non-surgery group developed cancer. The bariatric surgery group had lower numbers of new cases for multiple types of cancer.
Cancer Development Over 10 Years
The researchers found significant drops in four specific cancers linked to obesity: breast cancer, colon cancer, liver cancer, and ovarian cancer. Several other cancers were not significantly different between groups, including renal, rectal, and endometrial cancers.
Why the risk of cancer drops after surgery for obesity is not completely understood, Chittajallu said, but bariatric surgery has been shown to lower excess inflammation, elevate insulin, and moderate hormone levels.
| Type of Cancer | # Cases After Surgery | # Cases Without Surgery |
|---|---|---|
| Breast | 501 | 751 |
| Colon | 201 | 360 |
| Liver | 969 | 2,198 |
| Pancreatic | 54 | 86 |
| Ovarian | 130 | 214 |
| Thyroid | 154 | 175 |
‘Makes Logical Sense’
Loren Laine, MD, moderator of the media briefing, described the study as “fascinating.”
“Obesity is clearly associated with a number of different cancers and that’s very important. So it makes logical sense that if you lose weight that you will reduce that risk,” said Laine, who is a professor of medicine and chief of digestive health at Yale University School of Medicine in New Haven, CT.
The investigators controlled for risk factors that also could contribute to cancer development, including smoking history, alcohol use, heart disease, and hormone therapies. Laine added it was likely that investigators could not control for all factors because they were limited to information available in the database.
Unanswered Questions
If future research shows that the more weight you lose, the more likely you are to have a reduction in cancer, “that would be fascinating,” Laine said. Also, it would be interesting to know if other approaches like weight loss medications could decrease the number of cancers too.
“We need more research to understand how bariatric surgery affects cancer risk,” Chittajallu said, “but the significant findings from this study suggest it’s an exciting avenue for further study.”