Most recent update: Thursday, November 30, 2017 - 11:56

Bariatric News - Cookies & privacy policy

You are here

Bariatric surgery and cancer

Bariatric surgery lowers cancer risk for severely obese patients

Overall, the risk of postmenopausal breast cancer dropped by 42 percent and while the risk for endometrial cancer dropped 50 percent in severely obese patients
The risk of colon cancer dropped 41 percent while the risk of pancreatic cancer was lowered by 54 percent

Severely obese patients who undergo bariatric surgery lower their risk of developing cancer by at least a third, according to a University of Cincinnati (UC) College of Medicine researcher leading a large retrospective cohort study of patients in the western US.

Daniel Schauer

"We found having bariatric surgery is associated with a reduced risk of cancer, especially obesity-associate cancers including postmenopausal breast cancer, endometrial cancer, pancreatic cancer and colon cancer," said Daniel Schauer, associate professor in the UC Division of General Internal Medicine and lead researcher. "What's surprising is how great the risk of cancer was reduced."

Obesity has been strongly associated with many types of cancer, although few studies have examined the relationship between bariatric surgery and cancer risk. Therefore the paper, ‘Bariatric Surgery and the Risk of Cancer in a Large Multisite Cohort’, published online in the Annals of Surgery, sought to determine whether bariatric surgery is associated with a lower risk of cancer.

The study reviewed medical data of 22,198 individuals who had bariatric surgery and 66,427 non-surgical patients between 2005 and 2012 with follow-up through 2014 matched on sex, age, study site, body mass index, and Elixhauser comorbidity index. It pulled data from large integrated health insurance and health care delivery systems from five study sites operated by Kaiser Permanente in Southern California, Northern California, Oregon, Colorado and Washington. Multivariable Cox proportional-hazards models were used to examine incident cancer up to 10 years after bariatric surgery compared to the matched nonsurgical patients.

After a mean follow-up of 3.5 years, they researchers identified 2,543 incident cancers. Patients undergoing bariatric surgery had a 33% lower hazard of developing any cancer during follow-up [hazard ratio (HR) 0.67, 95% confidence interval (CI) 0.60, 0.74, p<0.001) compared with matched patients with severe obesity who did not undergo bariatric surgery, and results were even stronger when the outcome was restricted to obesity-associated cancers (HR 0.59, 95% CI 0.51, 0.69, p<0.001).

Outcomes

Among the obesity-associated cancers, the risk of postmenopausal breast cancer (HR 0.58, 95% CI 0.44, 0.77, p<0.001), colon cancer (HR 0.59, 95% CI 0.36, 0.97, p=0.04), endometrial cancer (HR 0.50, 95% CI 0.37, 0.67, p<0.001), and pancreatic cancer (HR 0.46, 95% CI 0.22, 0.97, p=0.04) was each statistically significantly lower among those who had undergone bariatric surgery compared with matched non-surgical patients.

Overall, the risk of postmenopausal breast cancer dropped by 42 percent and while the risk for endometrial cancer dropped 50 percent in severely obese patients. The risk of colon cancer dropped 41 percent while the risk of pancreatic cancer was lowered by 54 percent.

"Cancer risks for postmenopausal breast cancer and endometrial cancer are closely related to oestrogen levels," explained Schauer. "Having weight loss surgery reduces oestrogen level."

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, he added.

"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," said Schauer. "The study provides an additional reason to consider bariatric surgery."

The study found no significant association between bariatric surgery and cancer risk among men. Schauer said this may be because the vast majority of study patients are female and at least two of the cancers most impacted by bariatric surgery, postmenopausal breast cancer and endometrial cancer, affect women only.

“In this large, multisite cohort of patients with severe obesity, bariatric surgery was associated with a lower risk of incident cancer, particularly obesity-associated cancers, such as postmenopausal breast cancer, endometrial cancer, and colon cancer,” the researchers concluded. “More research is needed to clarify the specific mechanisms through which bariatric surgery lowers cancer risk.”

Want more stories like this? Subscribe to Bariatric News!

Bariatric News
Keep up to date! Get the latest news in your inbox. NOTE: Bariatric News WILL NOT pass on your details to 3rd parties. However, you may receive ‘marketing emails’ sent by us on behalf of 3rd parties.