During his joint address to Congress on Tuesday, President Donald Trump spoke about childhood cancer rates, saying it was a priority of his administration to tackle this issue.

“Since 1975, rates of child cancer have increased by more than 40 percent,” Trump said during his speech. “Reversing this trend is one of the top priorities for our new presidential commission to Make America Healthy Again, chaired by our new secretary of Health and Human Services, Robert F. Kennedy Jr.”

The president also took time to highlight a 13-year-old brain cancer survivor, whom he invited as a special guest to attend his address.

Although it’s unclear where Trump got the 40% figure, data shows that childhood cancer rates have indeed been increasing over the past several decades. However, a pediatric oncologist told ABC News that there’s important context missing in that statement, such as the effect of advances in early detection and possible environmental factors.

“It’s accurate to say that these diagnoses have gone up in the tracking data,” Dr. John Prensner, an assistant professor of pediatrics and of biological chemistry in the department of cancer biology at the University of Michigan School of Medicine, told ABC News. “I think the context for these numbers is incredibly important and that’s what I think has been left out, perhaps, of the conversation.”

Additionally, childhood cancer treatments have been improving and the number of childhood cancer survivors is increasing, Prensner said.

What the data shows

A study published early this year in the journal PLOS One that was conducted by researchers in the U.S., Germany and Jordan found that childhood cancer rates in America have increased by approximately 33% since 1975.

The study found that the incidence of childhood cancer rose from 14.23 cases per 100,000 children between 1975 and 1979 to about 18.89 cases per 100,00 children between 2010 and 2019.

The increase was found in certain types of cancer including leukemias, lymphomas, brain tumors, hepatic tumors, and gonadal germ cell tumors, according to the study.

Additionally, a report by the U.S. Environmental Protection Agency found that over the past 40 years, the number of children diagnosed with leukemia has increased by about 35%.

These trends mirror what has been seen in older populations, with cancer rates also increasing in adults under age 50.

Why rates are increasing

Prensner said scientists believe there are many likely reasons why childhood cancer rates are increasing.

One reason is better detection and the dramatic improvement in medical tests over the past several decades, according to Prensner, who said many of the tests that are now commonly used didn’t exist 50 years ago.

“These include dramatic, dramatic improvements in the ways that we can image patients with CAT scans and MRI scans,” Prensner told ABC News. “This includes improvements in the way that we monitor and screen certain patients. We have much more information now about patients who may have what’s called a cancer syndrome, meaning they’re at a higher risk to develop cancer.”

“In those patients, we actively monitor them to be able to make early diagnoses before cancers are able to spread, and so those patients may not have been monitored in prior decades because we didn’t have that scientific information,” he added.

Prensner said he is not an expert in the risk of cancer from environmental exposures but that data suggests those factors may also be playing a role in the increase of childhood cancer rates.

A study from March 2024 that analyzed over 200 previous studies found that exposure to pesticides, hazardous air pollutants, chemicals like benzene, and vehicular emissions has been linked to higher rates of childhood cancers, particularly leukemia.

Decrease in childhood mortality

While childhood cancer rates have increased, childhood cancer mortality rates have significantly declined over the past decades. Between 2001 and 2021, the cancer death rate for U.S. children and teens aged 19 and younger decreased by 24%, from 2.75 to 2.10 per 100,000 individuals, according to data from the Centers for Disease Control and Prevention (CDC).

Prensner said there are close to 500,000 childhood cancer survivors in the U.S., many of whom are now adults, indicating that more children are surviving cancer, likely due to advancements in medical treatments and early detection.

“There are some types of childhood cancers that are associated with congenital anomalies or birth defects, and patients who are born with those different disorders also receive better care now, such that they may have a higher cancer rate now, because they’re living longer, whereas they may not have lived nearly as long in 1980,” Prensner said.

In a statement to ABC News, Lisa Lacasse, president of the American Cancer Society Cancer Action Network, said she was “encouraged” to see President Trump shine a light on childhood cancer rates.

“While pediatric cancer incidence has increased in the last few decades, the cancer mortality rate among children and adolescents younger than 20 years declined by more than 50% from 1975 to 2022, according to the National Cancer Institute; though lasting effects from treatment persist,” Lacasse said. “This progress in survival has been possible thanks to investments in research and breakthroughs in treatment.”

Dr. Suhas Kochat is an internal medicine resident at Novant Health in North Carolina and member of the ABC News Medical Unit.