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Being overweight may raise risk of eight more cancers, review finds

BMJ 2016; 354 doi: https://doi.org/10.1136/bmj.i4650 (Published 25 August 2016) Cite this as: BMJ 2016;354:i4650
  1. Susan Mayor
  1. London

Being overweight is associated with increased risk of eight further cancers, including stomach and liver cancers, in addition to those previously linked with excess weight, a large review has found.1

The International Agency for Research on Cancer (IARC) Working Group reviewed more than 1000 studies investigating cancer risk and excess body weight to update previous findings. Most of the studies were observational studies; few randomised trials looked at weight loss and cancer risk.

The review, reported in the New England Journal of Medicine, found evidence linking excess body weight to increased risk of eight cancers: cancers of the gastric cardia (stomach cancer), liver, gallbladder, pancreas, ovary, and thyroid, as well as multiple myeloma and meningioma. These added to the group’s previous findings that had linked excess weight to a higher risk for cancers of the breast, colon, oesophagus, kidney, and uterus.

“The burden of cancer due to being overweight or obese is more extensive than what has been assumed,” said Graham Colditz, of the Washington University School of Medicine in St Louis, Missouri, who chaired the IARC Working Group. “Many of the newly identified cancers linked to excess weight haven’t been on people’s radar screens as having a weight component.”

The researchers found a dose-response relation with excess weight among most of the cancers in the newly expanded list, and risks were increased similarly in men and women. The team said that excess fat may promote inflammation and may lead to the overproduction of oestrogen, testosterone, and insulin, all of which can drive cancer growth.

Colditz said, “Lifestyle factors such as eating a healthy diet, maintaining a healthy weight and exercising, in addition to not smoking, can have a significant impact on reducing cancer risk. Public health efforts to combat cancer should focus on these things that people have some control over.”

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