Bariatric surgery (reducing the size of the stomach) for severely obese women could lower their breast cancer risk by more than a third, according to a new study.

The research from University of Cincinnati College of Medicine has been published in the journal the Annals of Surgery and reviewed the medical data of more than 100,000 people in the United States.   

Lead researcher, Dr Daniel Schauer, says the results were surprising.

"We found having bariatric surgery is associated with a reduced risk of cancer, especially obesity-associated cancers including postmenopausal breast cancer, endometrial cancer, pancreatic cancer and colon cancer.  What’s surprising is how great the risk of cancer was reduced,” he says.

The study reviewed the medical data of 22,198 individuals who had bariatric surgery and 66,427 nonsurgical patients between 2005 and 2012 with follow-up in 2014. More than 80 percent of patients in the study were women.

The researchers found patients who had bariatric surgery had:

  • a 33% lower risk of developing any cancer during follow-up
  • a 42% lower risk of developing post-menopausal breast cancer 
  • a 50% lower risk of developing endometrial cancer
  • a 41% lower risk of colon cancer
  • a 54% lower risk of pancreatic cancer.

"Cancer risks for postmenopausal breast cancer and endometrial cancer are closely related to estrogen levels and having weight loss surgery reduces estrogen levels,” Dr Schauer says.

He says bariatric surgery helps reduce the risk of diabetes and insulin levels which may be a risk factor for pancreatic cancer, while the mechanisms for colon cancer are more complicated.  

"I think considering cancer risk is one small piece of the puzzle when considering bariatric surgery, but there are many factors to consider. Reductions in diabetes, hypertension and improvements in survival and quality of life are reason enough,” says Schauer. "The study provides an additional reason to consider bariatric surgery.”

New Zealand’s Ministry of Health says nearly a third of New Zealanders are obese – more than 1.3 million people and scientists believe obesity is associated with up to 40 percent of all cancers.

7 Dec 2017

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