People who are overweight in their 20s and then become obese later in life may be three times more likely to develop oesophageal or stomach cancer, according to new research.
The research from the United States, published in the British Journal of Cancer, suggests that putting on weight over the years can be a particularly strong risk factor for two cancers that have very poor survival rates. Only a quarter (26%) of those diagnosed with cancer of the oesophagus or cancer of the upper stomach survive for five years.
Researchers from the National Cancer Institute in Bethesda, in the US, studied data from about 400,000 people to work out whether weight gain was linked to these two cancers of the digestive system which have been rapidly increasing in recent years.
They found a strong link to being overweight at the age of 20, which increased the risk of these cancers by between 62% and 76%, compared to people of a healthy weight. They also found that people who gained more than three stone – 20 kilos – were twice as likely to develop oesophageal cancer as those whose weight remained fairly stable.
The strongest links were found among those who reported being overweight in their twenties and then progressed to obesity in later life. Participants in this group had a three times increased risk of developing either stomach or oesophageal cancer.
“This study highlights how weight gain over the course of our lives can increase the risk of developing these two cancer types, both of which have extremely poor survival [rates],” said the study leader Dr Jessica Petrick.
“Carrying excess weight can trigger long-term reflux problems and heartburn that can lead to cancer. It can also change the levels of sex hormones, such as oestrogen and testosterone, cause levels of insulin to rise, and lead to inflammation, all of which are factors that have been associated with increased cancer risk.”
About 5,600 people are diagnosed with one of the two cancers every year in the UK. They are rarer than other cancers which are linked to obesity, such as bowel, breast and liver cancer, but as with pancreatic cancer which is also linked to weight, the low survival rate makes it important for people to know how they can help reduce their risk, say experts.
The study “further highlights the importance of keeping a healthy weight throughout life to reduce the risk of developing these cancers. Small steps like taking the stairs more often, keeping an eye on portion sizes and switching to sugar-free drinks are simple things we can all do to help keep a healthy weight,” said Sarah Williams, health information manager at Cancer Research UK (CRUK).
After smoking, being overweight or obese is the biggest single preventable cause of cancer, says CRUK. It is partly responsible for 18,100 cancer cases every year.
The researchers asked the participants to remember how much they weighed at the age of 20 and 50, as well as their weight when they joined the study – which is a possible weakness, they say, although it has been shown that people tend to report their past weight accurately. They then factored in their height to calculate their body mass index – a measure of how overweight a person is – and how it changed over time.
They say it is not yet clear why obesity is linked to these two digestive cancers, but it is possible that excess weight may increase the pressure on the abdominal organs, promoting gastroesophageal reflux disease which is a risk factor for oesophageal cancer.
Weight gain over adult life linked to greater digestive cancer risk, says study
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