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What do we already know?

It is important to identify groups of people who have a higher risk of developing cancer.

  • People who are heavily over weight (obese) are known to be at increased risk of cancer.
  • It is likely that surgery to treat obesity will also reduce a person’s risk of cancer.
  • However, a Swedish study has suggested surgery to treat obesity may increase the risk of bowel cancer.

What did we do in our study

Our study looked at routine healthcare data from NHS patients to see if surgery to treat obesity made a difference to the risk of developing cancer.

What did we find for bowel, endometrial and kidney cancer?

Over a million obese patients were found and, as expected, they had an increased risk of bowel, endometrial and kidney cancer compared to the non-obese population.

Of the million obese patents:

  • 3,280 developed bowel cancer.
  • 43 of these cancers were in those who had previously had surgery to treat their obesity. Because only 4% of the obese patients had such surgery we did not have enough patients to detect an effect on the chances of subsequently developing bowel cancer.

What about other cancers?

We did have more definitive answers for other cancers. Our analysis showed that:

  • Those who had surgery had a decreased risk of breast cancer, compared to those who did not have surgery.
  • Surgery made no difference to the risk of endometrial and kidney cancers.

Project Outputs

Publication: Obesity surgery and risk of colorectal and other obesity-related cancers: An English population-based cohort study, Ariadni Aravani, Amy Downing, James D. Thomas, Jesper Lagergren, Eva J.A. Morris, Mark A. Hull, Cancer Epidemiology, Volume 53, April 2018, Pages 99-104

Background work/relevant papers

Cancer risk after obesity surgery – is colorectal cancer a ‘special case’? Hull MA, Markar SR, Morris EJA, Nature Rev Gastroenterol Hepatol 2018; 15(11):653-654