Obesity-related cancer cases increasing in both young, older adults: Study

Cancer cases linked with obesity, previously observed as rising among the youth, could also be increasing in both young and older adults worldwide, according to a global analysis.

Researchers from The Institute of Cancer Research and Imperial College London cautioned that new studies focusing solely on younger adults for rise in cancer cases should be carefully considered.

The study, published in the journal Annals of Internal Medicine, which examined annual cancer incidence from 2003 to 2017 found that five obesity-related cancers -- thyroid, breast, kidney, endometrial, and blood (leukaemia) --  have risen in both adults aged 20–49 and those 50 and older.

All the five cancers are related to obesity, the team said.

Data from 42 countries across Asia, Europe, Africa, North and South America, and Australasia drawn from the International Agency for Research on Cancer's 'GLOBOCAN' database was analysed.

Rates of cancer incidence were found to have increased among younger adults in over three-fourths of the countries studied for thyroid, breast, colorectal, kidney, endometrial cancer and leukaemia.

For colorectal cancer, however, the rise in cases among the younger adults were more than that of older adults in nearly 70 per cent of the countries analysed.

The researchers attributed the trend to an exposure to new cancer-causing agents or an effective screening among older adults.

For liver, oral, oesophageal, and stomach cancer, the rates of incidence were lower in younger adults in more than half of the countries studied.

"Cancer incidence rates increased for several cancer types in many of the countries studied; however, other than colorectal cancer, these increases occurred in both younger and older adults," the authors wrote.

The cancer types seen to be increasing among both younger and older adults in most countries were all related to obesity, with endometrial and kidney cancer being the most strongly associated with obesity, they added.

The team said the results indicate that changes in exposures resulting in higher cancer rates case rates could be common across age groups, and not limited to younger adults.

Cancer types previously seen rising in younger adults are increasing in both younger and older adults, and the implications of focusing new research studies for these cancer types only on younger adults should be carefully considered, the researchers said.