Childhood cancer is particularly tragic, but fewer and fewer children die of the disease, which continues a trend seen since the 1970s, finds a new report released this past weekend by the National Center for Health Statistics (NCHS).

Researchers analyzed data on national childhood cancer death rates stretching back to 1999. They found that rates have decreased across the board among different genders, races, and types of cancer. In 1999, 2.85 out of every 100,000 children under the age of 19 died from cancer, compared to 2.28 out of 100,000 children in 2014, a 20 percent decline. The decline wasn’t equally distributed, however. While leukemia and brain cancer accounted for more than half of all deaths, brain cancer overtook leukemia to become the biggest single killer, causing 3 out of every 10 cancer deaths in 2014.

“The shift from leukemia to brain cancer as the leading site of cancer death is a noteworthy development in the history of childhood cancer as it was always leukemia until quite recently," lead author Sally Curtin, a demographer and statistician at the NCHS, told LiveScience.

The good news continues a trend in declining rates seen since the 1970’s, Curtin and her colleagues noted. And although the current study can’t provide a specific reason for the decline, it’s almost certain that ongoing medical advances in cancer detection and treatment play a large role, they wrote. However, there has been less progress in treating cases of brain cancer than with leukemia, possibly explaining the shift in mortality.

Cancer death rates for children and adolescents aged 1-19 years, by sex, 1999-2014. Despite the overall good news, boys remain 30 percent more likely to die of cancer than girls as of 2014 Curtin, et al. National Center for Health Statistics

While death rates among blacks and whites have taken a similar drop over time, boys remained 30 percent more likely to die of cancer than girls as of 2014. Similarly, while the decline was pronounced among all age groups, children ages 15 to 19 remained more likely to die of cancer than any other group.

In recent years, there have been promising efforts to create even more advanced methods of childhood cancer detection, such as diagnostic blood tests, and promote better outcomes following treatment. Efforts to create chemotherapy drugs that can more directly attack cancerous cells in the brain have also shown some hope. Coupled with existing technology and education, these advances will hopefully only further drive down cancer death rates.

Source: Curtin S, Miniño A, Anderson R. Declines in Cancer Death Rates Among Children and Adolescents in the United States, 1999–2014. National Center for Health Statistics. 2016.