Surge in obesity-linked cancers among older adults, global study warns

A major international study has found that obesity-related cancers are rising sharply among both younger and older adults, challenging long-held beliefs about which age groups are most at risk.

The research, published in the Annals of Internal Medicine, suggests that obesity is now driving increases in several common cancers across the globe, affecting people well into later life.

Scientists from Imperial College London and other institutions analysed cancer data collected over two decades from 42 countries, using figures from the International Agency for Research on Cancer’s GLOBOCAN database. The data, covering the years 2003 to 2017, included regions across Asia, Europe, Africa, the Americas and Australasia.

The researchers examined 13 cancers previously identified as rising among younger adults, including breast, colorectal, kidney, thyroid, endometrial and leukaemia. They then compared trends among people aged 20 to 49 with those aged 50 and over.

To their surprise, the team found that six of these cancers, leukaemia, thyroid, breast, endometrial, colorectal and kidney, were increasing in both younger and older adults in nearly three-quarters of the countries studied.

“These results suggest that obesity-linked cancers are no longer confined to specific age groups,” the authors said. “The risk appears to extend across adulthood, highlighting the far-reaching impact of excess body weight.”

Scientists have long known that obesity can contribute to cancer by triggering inflammation, disrupting hormones, and altering how cells grow and divide. Fat tissue also acts as a hormone-producing organ, and when its activity becomes unbalanced, it can encourage cells to multiply more rapidly, increasing the risk of tumours.

The study found the strongest links between obesity and cancers of the uterus and kidney.

However, not all trends were upwards. Rates of liver, oral, oesophageal and stomach cancers declined among younger adults, which researchers attributed to successful public health efforts to reduce smoking, alcohol use and viral hepatitis.

Bowel cancer rates, on the other hand, rose more sharply among younger adults than older ones. Researchers suggested that older adults may be benefiting from better screening, while younger people could be more exposed to modern environmental or dietary risk factors.

Experts say the findings highlight the urgent need to tackle rising obesity levels and to develop prevention strategies aimed at people of all ages.