Whether it's because more patients are getting earlier screenings or if there's a new biological risk, scientists with the American Medical Association aren't sure why higher rates of early onset cancer among younger patients are happening.
Researchers found between 2010 and 2019, over 500,000 patients were diagnosed with early onset cancer. About 63% were women between the ages of 40 to 49.
The findings are unusual as cancer is typically thought of as a disease occurring in the elderly population. That remains true, according to the data, but the findings show increases in cancer rates in young populations.
What the data means
The incidence — the rate of newly diagnosed cases of disease — diagnosed in people younger than 50 increased between 2010 and 2019. However, new cases for men showed a decrease.
The data doesn't explain why, said Bently Doonan an assistant professor of oncology and hematology at the University of Florida.
“What this data is trying to do is just start the conversation, it's trying to identify risk, or identify age groups within a given area, and really just look for tracks,” Doonan said. "It's important to remember that this isn't individualized to any one person or any one region or any one area. ... Oftentimes, what we're looking for in these larger studies are, 'What are the bigger trends across the population?' "
The study also revealed breast cancer recorded the highest total of cases among all early onset cancers. However, the American Cancer Society published data last year showing the mortality rate of breast has declined in the last 30 years by 43%.
AMA's data further showed gastrointestinal cancers had the fastest-growing incidence rates of any cancer. The greatest increase in incidence rates for early onset gastrointestinal cancers occurred in those aged 30 to 39, the data showed.
Are rising rates of obesity connected?
No definitive explanations came from the study, but increases in early onset cancers were likely associated with the increasing rate of obesity as well as changes in environmental exposures, such as smoke and gasoline, sleep patterns, physical activity, microbiota, and transient exposure to carcinogenic compounds.
Doonan pointed out that early rates of cancer line up with the earlier rates of obesity scientists are observing. According to the Centers for Disease Control and Prevention, obesity prevalence is 12.7% among 2- to 5-year-olds, 20.7% among 6- to 11-year-olds, and 22.2% among 12- to 19-year-olds.
"If you took that same start point and moved it from, say, obesity and the risks of inflammation in your 30s or 40s and you bring it back to being a teenager, well add 10, 20 or 30 years onto being a teenager, and now all of a sudden there's cancer, but you're in your 40s," Doonan said. "That's a big risk factor that we think contributes to known cancers like colorectal cancer and breast cancer, where they can be very heavily driven by things like obesity, lack of activity, lack of exercise and a sedentary lifestyle."
According to the National Library of Medicine, childhood obesity has doubled in the last three decades and is expected to continue rising.
"The scary thing is that if you look at outside of this cancer data, and you look at population level data at the rate of the of obesity and overweight children or teenagers, that's higher than it's ever been and continues to increase," Doonan said.
The AMA's data doesn't directly link obesity and cancer, but scientists highly suspect the correlation and will be looking at future studies.
In the meantime, Doonan said there are still ways people can protect themselves.
"The biggest common sense strategy that we can do is maintaining a healthy lifestyle and a healthy balance to our weight. So not to go to the extremes, it's just much more of common sense to limit those things to prevent that stress that we put on our body,” Doonan said.
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