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February 4, 2019, 19:32 GMT / Source: Good Medical

By Linda Carroll

Reflecting the decades-long increase in obesity in the United States, cancers believed to be at least partially overweight are also increasing among people younger than 50, a new study suggests.

Rates for six of the 12 cancers related to obesity have increased in successive generations of young adults, with the largest increases in the youngest age groups, researchers reported Sunday in The Lancet Public Health.

The new study may serve as a warning that if the obesity epidemic persists, there will be an explosion of these fat-sensitive cancers in the coming years, said the senior author of the study, Dr. ir. Ahmedin Jemal, scientific vice president of surveillance and health services research at the American Cancer Society.

"This finding signals an increased burden of obesity-related cancers in older adults in the future and calls for actions to alleviate this burden," he said in an e-mail.

The researchers analyzed data from a central database of state cancer registries, with an emphasis on new diagnoses of 30 types of cancer, 12 of which are associated with obesity, from 1995 to 2014. They had complete data from 25 states representing approximately two-thirds of the US population.

In that 20-year period there were approximately 14.7 million new cases of the 30 cancers. The incidence rates decreased for at least eight cancers, including smoking-related and HIV-associated cancers.

But for six of the 12 obesity-related cancers – colorectal, endometrial, gallbladder, kidney, pancreas and multiple myeloma – there was a steady increase in incidence over the years, with greater increases in younger adults.

The annual increase in new cases of kidney cancer, for example, was 6.23 percent among people aged 25-29 years, but about 3 percent in the age group 45-49 years. Similarly, the incidence of pancreatic cancer increased 4.3 percent per year for 25- to 29-year-olds, but less than 1 percent per year among 45-49 year-olds.

Overall, the percentages of colorectal, endometrial, pancreatic and gallbladder cancers in millennials – young adults born around 1985 – were about double the percentages seen in people born at the same age in the 1950s, the researchers note.

Especially noticeable was the increase in kidney cancer. Millennials were almost five times as likely as baby boomers to get kidney cancer.

In contrast, for all but two of the 18 cancers that are unrelated to obesity, the percentages stabilized or decreased in successive younger birth cohorts.

Jemal said he hopes the new findings will sound an alarm to doctors treating young adults. "Less than half of the physicians in primary health care regularly assess the body mass index, despite national screening recommendations," he said. "Furthermore, only a third of patients report a diagnosis or advice for weight loss."

Measures in the field of public health, such as restrictions on advertising unhealthy low-calorie foods, can also help, as well as more campaigns to promote healthy lifestyle choices, Jemal said.

The issue of cancer obesity is a very important topic, as we have had an obesity crisis for several decades now, "said John Jakicic, a professor and director of the Healthy Lifestyle Institute at the University of Pittsburgh in Pennsylvania. "At some point we started to see that diabetes followed with obesity, what we see now is something similar with regard to certain cancers."

Cancer prevention probably means preventing other things that can cause cancer to precipitate & # 39 ;, said Jakicic, who was not involved in the study. And although researchers do not yet know exactly how obesity can increase cancer rates, it is critically important & # 39; to see observational studies showing a connection between these two, he noted.