(HealthDay)—Weight-loss surgery could help some severely obese people reduce their risk for cancer by at least 33 percent, a new study suggests.
The researchers examined medical data compiled by health insurance and health care delivery systems in the western United States, including Southern California, Northern California, Oregon, Washington and Colorado.
The analysis included data on nearly 22,200 people who had weight-loss surgery between 2005 and 2012, and over 66,400 people who didn't have the surgery. More than 80 percent of the study participants were women.
Within 3.5 years after their surgery, about 2,500 people had developed cancer, the findings showed.
The study found that patients who'd had weight-loss surgery, compared with those who had not had the surgery, were one-third less likely to have developed cancer, particularly the types of cancer related to obesity. Obesity is associated with up to 40 percent of all cancers diagnosed in the United States, the study authors explained.
However, the study found no significant association between cancer risk and weight-loss surgery among the men in the study. The researchers pointed out that at least two of the cancers found to be affected by weight-loss surgery only affect women—breast cancer and endometrial cancer.
"We found having bariatric [weight-loss] surgery is associated with a reduced risk of cancer, especially obesity-associated cancers including postmenopausal breast cancer, endometrial cancer, pancreatic cancer and colon cancer," said lead researcher Dr. Daniel Schauer. He's an associate professor at the University of Cincinnati College of Medicine's division of general internal medicine.
"What's surprising is how great the risk of cancer was reduced," he said in a university news release. But the study did not prove that weight-loss surgery caused the chances of certain cancers to drop.
But the reduced risk seen was significant. The risk for breast cancer among postmenopausal women dropped by 42 percent. Very obese women's risk for endometrial cancer fell by 50 percent, according to the report.
"Cancer risks for postmenopausal breast cancer and endometrial cancer are closely related to estrogen levels," Schauer said. "Having weight-loss surgery reduces estrogen level."
Other findings included a 41 percent reduced risk for colon cancer and a 54 percent reduced risk for pancreatic cancer for those who had weight-loss surgery.
The surgery helps prevent diabetes and lower insulin levels, which could lead to a lower risk for pancreatic cancer, according to the researchers.
"I think considering cancer risk is one small piece of the puzzle when considering bariatric surgery," Schauer said, "but there are many factors to consider. Reductions in diabetes, hypertension and improvements in survival and quality of life are reason enough. The study provides an additional reason to consider bariatric surgery."
More information: The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more on weight-loss surgery.
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