Weight-loss surgery reduces cancer risk to that of general population, study says

March 11 (UPI) -- Weight-loss surgery may significantly reduce the risk for colon cancer among people who are obese, a study published Wednesday in JAMA Surgery has found.

In an analysis of health data for more than one million people, researchers in France report that people who met the criteria for obesity -- based on body mass index greater than 30 -- but don't undergo bariatric surgery were 34 percent more likely to be diagnosed with colorectal cancers than the general public.

Obese adults who opt for the procedure have the same risk for these types of cancers as the general population, they authors added.

"The reason why we conducted this study is that obesity is known to increase cancer incidence -- and notably colorectal cancer incidence," co-author Laurent Bailly, a public health specialist at the Nice University Hospital in France, told UPI. "Bariatric surgery is an effective treatment of obesity. However, the association of this surgery with the colorectal cancer remains controversial."

BMI is a commonly used measure for obesity that factors in a person's height as well as their weight in kilograms. As UPI reported recently, more than 40 percent of U.S. adults meet the criteria for obesity based on BMI.

Bariatric surgical procedures are designed to induce weight loss by restricting the amount of food the stomach can hold.

In their review of patient records for just over 1 million French adults, Bailly and his colleagues found 13,052 cases of colorectal cancers -- a rate of 1.2 percent -- and 63,649 colorectal benign polyps were diagnosed.

The rate of colorectal cancer diagnoses among those who were obese and underwent bariatric surgery was was 0.6 percent, compared to 1.3 percent in those who did not have the procedure.

Predictive modeling developed by the research team indicated that there would be 9,417 cases of colorectal cancers among those who were obese and did not have bariatric surgery when, in fact, there were 12,629 -- 34 percent more than the authors' projections. Conversely, among those who were obese and had surgery, the models predicted 428 cases, with there 423 cases found among surgical patients.

In all, the authors found there were fewer new diagnoses of colorectal cancer following the weight-loss procedure called gastric bypass -- 123 out of 22,343 patients, or 0.5 percent -- and sleeve gastrectomy -- 185 out of 35,328 patients, or 0.5 percent -- than after adjustable gastric banding -- 115 out of 16,460 patients, or 0.7 percent.

"Following bariatric surgery, individuals with obesity share the same risk of colorectal cancer as the general population, Bailly said. "Whereas, for patients who did not undergo bariatric surgery, the risk of developing a colorectal cancer is above that of the general population."

For groups at higher risk for these cancers, such as adults between 50 and 75 years of age, he added, "all of them should be offered a screening test regularly."