Modeling the Incidence of Secondary Malignancy Related to Ionizing Radiation Use in the Management of Nephrolithiasis

Abstract

ObjectiveTo model the risk of secondary malignancy and associated mortality due to ionizing radiation from the evaluation and management of nephrolithiasis. MethodsA PUBMED-based literature search was performed to identify model inputs, specifically annual incidence of nephrolithiasis sub-stratified by age and gender and radiation exposure associated with nephrolithiasis episodes. Estimates of age and gender specific radiation-induced malignancy and mortality rates were obtained from the BEIR VII Phase 2 report with dose extrapolation using the linear no-threshold model. ResultsIncidence of new diagnoses of nephrolithiasis ranged from 42/100,000 in males 20-30 years old to 248/100,000 in males 60-70 years old. Radiation exposure per nephrolithiasis episode was 37.3 mSv over a 2-year period. Data regarding average stone episodes per patient with nephrolithiasis was limited and conservatively estimated at 1.5. Modeled lifetime attributable risk of secondary malignancy and subsequent mortality in individual stone patients ranged from 0.096% and 0.085%, respectively, in males over the age of 70 to 0.59% and 0.39% in females 20-30 years old. In the USA, overall incidence of secondary malignancy and associated mortality related to nephrolithiasis management was calculated to be 862.7 and 545.3 cases/year, respectively. ConclusionThis model suggests that ionizing radiation from the management of nephrolithiasis carries a small but significant risk of causing secondary malignancy. This knowledge must be considered when using modalities that involve radiation in the diagnosis and therapeutic management of nephrolithiasis.