Cancer before age 50 is increasing. A new study looks at which types
[May 09, 2025]
By CARLA K. JOHNSON
Cancer before age 50 is rare, but increasing, in the United States and
researchers want to know why.
A new government study provides the most complete picture yet of
early-onset cancers, finding that the largest increases are in breast,
colorectal, kidney and uterine cancers. Scientists from the National
Cancer Institute looked at data that included more than 2 million
cancers diagnosed in people 15 to 49 years old between 2010 and 2019.
Of 33 cancer types, 14 cancers had increasing rates in at least one
younger age group. About 63% of the early-onset cancers were among
women.
“These kinds of patterns generally reflect something profound going on,”
said Tim Rebbeck of Dana-Farber Cancer Institute, who studies cancer
risk and was not involved in the research. “We need to fund research
that will help us understand."
The findings were published Thursday in Cancer Discovery, a journal of
the American Association for Cancer Research.
How many extra cancers are we talking about?
The researchers compared cancer rates in 2019 to what would be expected
based on 2010 rates.
Breast cancer made up the largest share of the excess cancers, with
about 4,800 additional cases. There were 2,000 more colorectal cancers
compared with what would be expected based on the 2010 rates. There were
1,800 more kidney cancers and 1,200 additional uterine cancers.
Reassuringly, death rates were not rising for most cancers in the young
adult age groups, although increasing death rates were seen for
colorectal, uterine and testicular cancers.
Why is this happening?
Explanations will take more research. The big databases used for the
study don't include information on risk factors or access to care.
Theories abound and a big meeting is planned later this year to bring
together experts in the area.
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A radiologist uses a magnifying glass to check mammograms for breast
cancer in Los Angeles, May 6, 2010. (AP Photo/Damian Dovarganes,
File)
 “Several of these cancer types are
known to be associated with excess body weight and so one of the
leading hypotheses is increasing rates of obesity,” said lead author
Meredith Shiels of the National Cancer Institute.
Advances in cancer detection and changes in screening guidelines
could be behind some early diagnoses.
For breast cancer, the trend toward women having a first child at
older ages is a possible explanation. Pregnancy and breastfeeding
are known to reduce risk.
It's not a uniform trend for all cancers
This isn't happening across the board. Cancer rates in people under
50 are going down for more than a dozen types of cancer, with the
largest declines in lung and prostate cancers.
Cigarette smoking has been declining for decades, which likely
accounts for the drop in lung cancer among younger adults.
The drop in prostate cancer is likely tied to updated guidelines
discouraging routine PSA testing in younger men because of concerns
about overtreatment.
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