'Shocking' rise in obesity-related cancers among young adults

Laura Donnelly
The study, using data covering more than half the population of the United States, found rates of most obesity-related cancers seeing a sharp rise in younger generations - Science Photo Library

Rates of obesity-fuelled cancers are now rising in successively younger age groups, a landmark study shows.

Experts said "shocking" levels of disease linked to growing waistlines across the globe threaten to reverse decades of progress in the war on cancer.

The Lancet study shows that rates of obesity-related cancers are rising faster in adults aged 25 to 49 than in older generations - despite the fact cancer is seen as a disease of old age.

The research, which examined 12 types of cancer linked to obesity, divided patients into five-year age groups from 25-29 to 80-84 years old.

In six of the main cancers - including bowel, pancreatic and kidney disease - it was found that the younger the age group, the greater the increase in incidence.

The major research used data covering more than half the population of the United States.

But British experts warned that trends in this country - where obesity rates are rising faster than the US - means there is a similar threat to Britain’s population.

The study, led by the American Cancer Society, considered 30 of the most common cancer types, and tracked trends among those diagnosed between 1995 and 2014.

They included 12 cancers linked to obesity, as well as 18 other types of disease where no such association has been found. 

While rates of most of the obesity-related cancers saw a sharp rise in younger generations - outpacing the rise in older generations, in six types of disease - no such trend was seen in the other types of cancer, where rates either remained stable or fell. 

For example, while annual rates of bowel cancer fell by 3.65 per cent in those aged 80 to 84, and by 2.96 per cent, in those aged 60 to 64, they rose by 2.41 per cent in those aged 25 to 29, and by 2.38 per cent in those aged 30 to 34.

Rates of pancreatic cancer continued to rise in all age groups, with an increase of 0.88 per cent among those aged 80 to 84 and 0.79 per cent among those aged 60 to 64. But this was dwarfed by the rate of increases in younger groups, with a 4.3 per cent rise among those aged 25 to 29, and an increase of 2.5 per cent in those aged 30 to 34.

And while rates of kidney cancer rose by 1.67 per cent among thosen aged 80 to 84, they increased by 6.23 per cent among those aged 25 to 29, the figures show.

Younger groups also saw higher increases in the rise of incidence in womb cancer, gallbladder disease and multiple myloma, compared with older groups. 

Researchers stressed that it remains the case that cancer is far more common in older age groups. But they said the trends showed the alarming impact of the obesity epidemic.

While the United States has the highest obesity levels in the world, the UK’s levels have risen by 92 per cent since 1991, compared with a rise of 65 per cent in the US, making it the sixth fattest nation in the developed world.

Two in three adults in the UK are overweight or obese, along with one in three children leaving primary school.

Researchers said the findings, published in The Lancet Public Health journal on World Cancer Day, suggested the trends could halt or reverse decades of progress achieved in lowering cancer mortality. 

One in 20 cases of cancer in the UK are linked to excess weight.

In some cancers, excess bodyweight during early adulthood could be a more important influence on cancer risk than weight gain in later life, research has found. 

Tam Fry, from the National Obesity Forum, said: "There was a time when Type 2 diabetes used to be considered a mid-life disease triggered by our obesity epidemic. But that has all changed with young adults and even children's lives blighted by the condition. 

"Shockingly, if the same is happening with cancer in the US it could already be happening here.  Such a discovery could negate our own recent advances in treating cancers but until the NHS seriously begins to screen for obesity, as recommended by the study's authors, we may not know. " 

Dr Ahmedin Jemal from the American Cancer Society, said: “Over the past few decades, death rates have been in decline for most cancers, but in the future obesity could reverse that progress, barring any interventions. 

“Younger generations are experiencing earlier and longer-lasting exposure to excess fat and to obesity-related health conditions that can increase cancer risk.”

She said the burden was likely to increase much more as the younger generations aged, when cancer is more likely to develop.

Lead author Dr Hyuna Sung said: “Obesity is associated with health conditions that can contribute to the risk of cancer. For example, diabetes, gallstones, inflammatory bowel disease, and poor diet can all increase the burden of cancer.”

She said a deterioration in the quality of the diet of younger generations was likely to be fuelling the rise.

“More than half of adults who were 20 to 49 years old between 2010 to 2012 reported poor dietary habits, such as eating little fruit, vegetables, whole grains, fish and shellfish at the same time as eating too much salt, fast food, and sugary drinks,” she said.