(CNN) — Childhood cancer diagnoses in the US have been trending up for more than a decade, according to a study published Tuesday in the Journal of the National Cancer Institute.

There were 14,381 new childhood cancer diagnoses in the US in 2019: about 177 new cases for every 1 million children and teens up to age 19. Incidence rates have dropped since reaching a peak in 2016 but are still about 8% higher than they were in 2003, when there were about 165 new cases for every 1 million children and teens.

“Overall, cancer is very rare in children and adolescents, and the increases were small,” said Dr. David Siegel, a pediatric oncologist and an epidemiologist with the US Centers for Disease Control and Prevention’s cancer division who was the lead author of the study. “Past studies have also reported increased survival rates. So the combination of increases in incidence and decreases in deaths means that there are more and more cancer survivors that need long-term care and resources.”

The researchers gave a detailed look at incidence rates by cancer type, age group, geographic region and other demographic breakdowns. Siegel says that this detailed data could be helpful to direct resources where they are needed most, particularly in terms of clinical trials for treatments and supportive care, and improve the lives of these patients.

Leukemia was the most commonly diagnosed childhood cancer, with new diagnoses increasing from 43 cases for every 1 million children in 2003 to 47 in 2019, according to CDC data. New diagnoses of lymphoma, liver tumors, bone tumors and thyroid carcinomas also increased.

However, melanoma diagnoses decreased, dropping from about 6 new cases per 1 million children in 2003 to about 3 in 2019.

For this study, the researchers used data from medical records that was compiled in the CDC’s federal cancer statistics database. All 50 states were reporting data by 2003, offering a complete picture of pediatric cancer in the US population. It takes a few years after a diagnosis for data to become available in the system, making 2019 the most recent year with data available at the time of the study.

This data lag could explain part of the recent dip in incidence rates, especially amid logistical challenges posed by the Covid-19 pandemic, Siegel said. But there is room for hope.

“It is very possible that there are some positive reasons why cancer [incidence] is decreasing,” he said. In the study, Siegel and his fellow authors point to a potential relationship between the lower rates of melanoma and public health interventions emphasizing the importance of sun protection during younger years.

“But we do have to interpret with caution, because there are some data artifacts that could come into play,” Siegel said.

Factors such as changes to cancer detection, reporting and risk factors also add to the complexity of the trends.

Because pediatric cancer is rare, a lot of data is needed to understand it, Siegel said. The Childhood Cancer STAR Act – focused on survivorship, treatment, access and research – was reauthorized this year with commitments through fiscal year 2028.

One goal of that legislation is to make pediatric cancer data accessible in a shorter timeframe.

“We’re hoping that the data will become more real-time and then more rapidly help clinicians use it to meet patient needs and improve outcomes,” Siegel said.