Surveillance for radiation-related late effects in childhood cancer survivors: The impact of using volumetric dosimetry.

BACKGROUND: Radiation-related screening guidelines for survivors of childhood cancer currently use irradiated regions (IR) to determine risk for late effects. However, contemporary radiotherapy techniques utilize volumetric dosimetry (VD) to determine organ-specific exposures, which could inform need for late effect surveillance.
METHODS: This cross-sectional cohort study involved patients treated for cancer using computerized tomography-planned irradiation at Children's Hospital Los Angeles from 2000-2016. Organs at risk were identified using both VD and IR. Under each method, Children's Oncology Group Long-Term Follow-Up Guidelines were applied to determine radiation-related potential late effects and their correlative recommended screening practices. Patients served as their own controls. Mean number of potential late effects per patient and recommended screening practices per patient per decade of follow-up were compared using paired t-tests; comparisons were adjusted for diagnosis and gender using random effects, repeated measure linear regression.
RESULTS: In this cohort (n = 132), median age at end of treatment was 10.6 years (range, 1.4-20.4). Brain tumor was the most common diagnosis (45%) and head/brain the most common irradiated region (61%). Under IR and VD, the mean number of potential late effects flagged was 24.4 and 21.7, respectively (-11.3%, p < 0.001); concordance between the two methods was 6.1%. Under VD, the difference in mean number of recommended screening practices per patient was -7.4% in aggregate but as large as -37.0% for diagnostic imaging and procedures (p < 0.001 for both).
CONCLUSION: Use of VD rather than IR is feasible and enhances precision of guideline-based screening for radiation-related late effects in long-term childhood cancer survivors.