Editorial: Lymphoma Survivors: Time to Rationalize Use of Diagnostic Radiation Dose

Abstract

Pediatric malignancy has a variable global incidence and in United States is about 125/million population[i]. Leukemia, brain tumor and malignant lymphoma are the most common childhood malignancy.  Over last three decades, there has been a phenomenal decline in pediatric cancer related mortality and lymphomas stand in upper tier. The reasons behind this success story are aggressive multimodality therapy, better supportive care during and after these therapies and judicious utilization of imaging at various stages of management. In lymphomas, radiation based imaging tools like contrast enhanced CT and hybrid positron emission tomography with CT (PET/CT) are the primary methods used worldwide. Radiation dose incurred by fluorodeoxy glucose (FDG) PET/CT with contrast is considerably higher than CT alone. A patient with lymphoma is used to have at least 2-3 FDG PET/CT scan during the course of treatment. For initial staging of lymphomas, FDG PET/C has sensitivities and specificities 96%–99% and 95%–100%, respectively (more sensitive than CT in detecting nodal and extranodal lesions including lesions in the spleen and bone marrow. For response monitoring, FDG PET/CT is used after 2-4 cycles (interim scan) and after completion of therapy (end of treatment). Although the interim scan is very sensitive in guiding the oncologists by detecting a non-responder and predicting the response after completion (due to its high negative predictive value which is near 100%) but has a limited positive predictive value (41-86%) and need further morphological imaging for validation[ii]. All these procedures share humongous contribution to radiation those to these children.

[i]. SchaapveldM, Aleman B, Eggermond A, JanusC,  Krol A, Maazen R, et al.  Second Cancer Risk Up to 40 Years after Treatment for Hodgkin’s Lymphoma. N Engl J Med 2015;373:2499-511

[ii]. Uslu L, Doing J, Link M, Rosenberg J, Quon A, Daldrup A, et al. Value of 18F-FDG PET and PET/CT for Evaluation of Pediatric Malignancies. J Nucl Med 2015; 56:274–86