Patterns of diagnostic imaging and cumulative radiation exposure among long-term young adult cancer survivors.

Abstract

6027 Background: Young adults surviving a diagnosis of malignancy have a considerable life expectancy, however, little is known about radiation exposure from diagnostic imaging in these patients. This study aims to describe patterns of imaging and radiation exposure in young adult cancer survivors (YAS) and cancer-free controls in Ontario, Canada. Methods: We conducted a population-based retrospective study. Young adults aged 20-44 diagnosed with an invasive malignancy between 1992 and 1999 who lived at least 5 years without recurrent disease were identified in the Ontario Cancer Registry. YAS were matched 1:5 to randomly selected cancer-free controls on calendar year of birth, sex, and geographic location. Radiological procedures were identified through Ontario Health Insurance Plan administrative data. The rate at which individuals underwent diagnostic procedures after surviving 5-years was compared between survivors and controls using Poisson regression. Cumulative radiation exposure due to computed tomography (CT) and standard x-ray were calculated. Results: 20,911 YAS and 104,524 controls had a median of 13.5 years observation time after cancer diagnosis/referent date. The rate of CT scanning after 5 year survival was higher in YAS (rate ratio= 3.59, 95% CI: 3.46 – 3.73) and varied according to malignancy type (Table). Over the course of diagnosis, treatment and surveillance to 10 years, the average YAS was exposed to 33.8 mSv of radiation, 4.4 times the radiation exposure an individual in the general population received. 47% of YAS cumulative dose was attributed to exposure 5 years or more after diagnosis. Conclusions: YAS undergo imaging and are exposed to diagnostic irradiation at a significantly higher rate than controls even after 5 years of recurrence free survival. Alternative imaging techniques not associated with exposure to radiation should be considered for these patients. [Table: see text]