# Patterns of diagnostic imaging and associated radiation exposure among long-term survivors of young adult cancer: a population-based cohort study

## TL;DR

Young adult cancer survivors undergo more diagnostic imaging and receive higher radiation doses than controls, even when surveillance is not needed.

## Contribution

Quantifies higher diagnostic imaging rates and radiation exposure in long-term young adult cancer survivors compared to controls.

## Key findings

- Survivors received CT imaging at a 3.49-fold higher rate than controls.
- Survivors had a mean radiation dose of 26 mSv from imaging, 4.57 times higher than controls.
- Increased imaging occurred during a period when routine surveillance is not typically recommended.

## Abstract

Survivors of young adult malignancies are at risk of accumulated exposures to radiation from repetitive diagnostic imaging. We designed a population-based cohort study to describe patterns of diagnostic imaging and cumulative diagnostic radiation exposure among survivors of young adult cancer during a survivorship time period where surveillance imaging is not typically warranted.

Young adults aged 20–44 diagnosed with invasive malignancy in Ontario from 1992–1999 who lived at least 5 years from diagnosis were identified using the Ontario Cancer Registry and matched 5 to 1 to randomly selected cancer-free persons. We determined receipt of 5 modalities of diagnostic imaging and associated radiation dose received by survivors and controls from years 5–15 after diagnosis or matched referent date through administrative data. Matched pairs were censored six months prior to evidence of recurrence.

20,911 survivors and 104,524 controls had a median of 13.5 years observation. Survivors received all modalities of diagnostic imaging at significantly higher rates than controls. Survivors received CT at a 3.49-fold higher rate (95 % Confidence Interval [CI]:3.37, 3.62) than controls in years 5 to 15 after diagnosis. Survivors received a mean radiation dose of 26 miliSieverts solely from diagnostic imaging in the same time period, a 4.57-fold higher dose than matched controls (95 % CI: 4.39, 4.81).

Long-term survivors of young adult cancer have a markedly higher rate of diagnostic imaging over time than matched controls, imaging associated with substantial radiation exposure, during a time period when surveillance is not routinely recommended.

The online version of this article (doi:10.1186/s12885-015-1578-1) contains supplementary material, which is available to authorized users.