Historical trends in the use of radiation therapy for pediatric cancers: 1973-2008.

PURPOSE: This study was undertaken to assess historical trends in the use of radiation therapy (RT) for pediatric cancers over the past 4 decades.
METHODS: The National Cancer Institute's Surveillance, Epidemiology, and End Results database of the 9 original tumor registries (SEER-9) was queried to identify patients aged 0 to 19 years with acute lymphoblastic leukemia, acute myeloid leukemia, bone and joint cancer, cancer of the brain and nervous system, Hodgkin lymphoma, neuroblastoma, non-Hodgkin lymphoma, soft tissue cancer, Wilms tumor, or retinoblastoma from 1973 to 2008. Patients were grouped into 4-year time epochs. The number and percentage of patients who received RT as part of their initial treatment were calculated per epoch by each diagnosis group from 1973 to 2008.
RESULTS: RT use for acute lymphoblastic leukemia, non-Hodgkin lymphoma, and retinoblastoma declined sharply from 57%, 57%, and 30% in 1973 to 1976 to 11%, 15%, and 2%, respectively, in 2005 to 2008. Similarly, smaller declines in RT use were also seen in brain cancer (70%-39%), bone cancer (41%-21%), Wilms tumor (75%-53%), and neuroblastoma (60%-25%). RT use curves for Wilms tumor and neuroblastoma were nonlinear with nadirs in 1993 to 1996 at 39% and 19%, respectively. There were minimal changes in RT use for Hodgkin lymphoma, soft tissue cancer, or acute myeloid leukemia, roughly stable at 72%, 40%, and 11%, respectively. Almost all patients treated with RT were given external beam RT exclusively. However, from 1985 to 2008, treatments involving brachytherapy, radioisotopes, or combination therapy increased in frequency, comprising 1.8%, 4.6%, and 11.9% of RT treatments in brain cancer, soft tissue cancer, and retinoblastoma, respectively.
CONCLUSIONS: The use of RT is declining over time in 7 of 10 pediatric cancer categories. A limitation of this study is a potential under-ascertainment of RT use in the SEER-9 database including the delayed use of RT.