Bariatric surgery may lower patients' risk of developing colorectal cancer, a research review suggests. Obesity has long been linked to increased risk of colorectal tumors and other types of cancer, as well as a greater risk for chronic illnesses like diabetes and heart disease. Losing weight is thought to reduce these risks. "Our findings further support . . . that these surgeries do in fact have an overall protective effect among the obese population in terms of reducing colorectal cancer," said Dr. Sulaiman Almazeedi of Jaber Al-Ahmed Hospital in Kuwait, who led the study. The researchers examined data from seven previous studies that followed more than 1.2 million patients for about 7 years, on average. Colorectal cancer was rare, developing in just 638 people during the study. Compared to obese individuals who didn't get bariatric surgery, those who did were 35% less likely to develop colorectal cancer, the researchers report in the British Journal of Surgery. "Obesity is one of the most preventable causes of early death and it, as an epidemic, should not be taken lightly," Almazeedi told Reuters Health by email. "Although lifestyle modifications and medical therapy have long been the cornerstone of this problem, bariatric surgery is proving day by day to be of vital importance in this battle." The studies in the analysis used a variety of methods and none was designed to prove bariatric surgery directly affects colorectal cancer risk. Researchers also lacked information on preoperative body mass index, postoperative weight loss, and type of bariatric surgery. "The primary explanation for reduction in cancer including colorectal cancer following bariatric surgery is the extent of weight loss which occurs," said Dr. Bruce Wolfe, a researcher at Oregon Health and Science University in Portland, who wasn't involved in the study. Earlier research suggests obese people need to lose 20% of their body weight to get the best outcome in terms of reducing the risk of cancer, Wolfe said by email. Bariatric surgery is the best way to accomplish this, he said. When people lose weight after bariatric surgery, many changes happen that impact cancer risk, said Dr. Daniel Schauer of the University of Cincinnati College of Medicine, in Ohio. "Perhaps most importantly for colorectal cancer risk, the body has less inflammation and many of the (tumor) growth factors associated with obesity are decreased," Schauer, who also wasn't involved in the study, said by email. "These are strongly related to the amount of weight loss." Data from this study were presented at the XXIV World Congress of the International Federation for the Surgery of Obesity and Metabolic Disorders, Madrid, Spain, September 2019. —Lisa Rapaport Source
