Gen Xers may be more likely to be diagnosed with cancer at 60 years old than their parents' generation was, a new study forecasts.
Scientists made this prediction after analyzing medical records from 3.8 million people in the U.S. who'd been diagnosed with different types of "invasive" cancer between 1992 and 2018. The term "invasive" refers to cancer that has spread from where it originated to surrounding tissue.
The researchers used these data to plot "age of onset" curves, which are a graphical way of visualizing how many people are diagnosed with cancer at a particular age — in this case, 60 years old. Age is plotted on the horizontal axis of the graph, while the number of people diagnosed with cancer is on the vertical axis. By connecting the dots between the data, the full trajectory of each type of cancer within the population can be captured, and scientists can make predictions about future patterns in diagnosis rates.
In the new study, published June 10 in the journal JAMA Network Open, researchers used these projections to estimate how many people born between 1908 and 1983 are likely to be diagnosed with cancer at a benchmark age of 60. These statistical models can uncover possible trends, but can't say why they're happening — for example, they don't take into account environmental factors that can drive cancer, or improvements in cancer screening and diagnostics.
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The team estimated that Gen Xers, born between 1965 and 1980, are less likely per capita to develop certain cancers at age 60 than baby boomers, born between 1946 and 1964. For women, these included lung and cervical cancers, while for men, these included lung, liver and gallbladder cancers. Some of these declines were already on the public health radar; rates of lung cancer, for instance, have been falling for decades, partly because fewer people are smoking.
The projected rates of many other types of cancers, however, were higher for Gen Xers at age 60 than boomers. For both sexes, these cancers included thyroid, kidney and colon cancers.
These rising figures canceled out any declining ones and ultimately resulted in an overall predicted increase in cancer rates across all sexes, races and ethnicities of Gen Xers. Men of Asian or Pacific Islander ancestry were the only exception to this trend.
The new study was unable to estimate cancer rates for generations younger than Gen Xers, such as Millenials, who were born between 1981 and 1996. That's because these age groups have yet to turn 60, while Gen Xers are just beginning to turn 60. That said, based on their projections, the study authors predict that it's likely that cancer rates in the U.S. will stay "unacceptably" high for decades, the authors wrote in the paper.
This is an "important study," as it combines data for many major cancers, Dr. Graham Colditz, deputy director of the Institute for Public Health at Washington University in St. Louis who was not involved in the research, told Live Science in an email.
Several studies have looked at one cancer at a time to reveal increasing rates of diagnosis, particularly in people under the age of 50, he said. However, this new analysis brings all these findings "into context."
For now, the new study only provides a top-line view of how cancer diagnosis rates may be increasing in younger generations in the U.S., based on statistical modeling. More research is needed to explain this emerging trend, Philip Rosenberg, co-senior study author and a senior investigator at the National Institutes of Health (NIH), told Live Science.
"It's pretty likely that rising obesity rates and increases in sedentary behavior may be responsible for some of the increases [in cancer rates]," Rosenberg said. A number of more recent environmental exposures, such as the invention of ultraprocessed foods in the 1980s, that are suspected to be implicated in cancer, could also play a role, he added.
At the same time, improvements in diagnosis and screening could partly explain soaring cancer diagnosis rates. This includes the detection of disease-specific molecules called biomarkers, and more recently, the use of artificial intelligence (AI) to analyze blood samples.
There are now also more higher quality, population-based cancer registries than ever, potentially making it easier to record cancer rates at a larger scale.
The reasons behind the projected trends will hopefully come with time, Rosenberg said. Once the reasons are known, officials could implement appropriate public health guidance to help drive cancer rates down, he said.
This article is for informational purposes only and is not meant to offer medical advice.
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