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


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Department of Surgery, Li Ki Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada. dalyco@smh.ca.
Corinne
C
Daly
Department of Surgery, University Health Network, Toronto, Canada. david.urbach@uhn.ca.|Institute for Clinical Evaluative Sciences, Toronto, Canada. david.urbach@uhn.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. david.urbach@uhn.ca.
David R
DR
Urbach
Institute for Clinical Evaluative Sciences, Toronto, Canada. stukel@ices.on.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. stukel@ices.on.ca.
Thérèse A
TA
Stukel
Institute for Clinical Evaluative Sciences, Toronto, Canada. paul.nathan@sickkids.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. paul.nathan@sickkids.ca.|Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Canada. paul.nathan@sickkids.ca.
Paul C
PC
Nathan
Department of Radiology, St. Michael's Hospital, Toronto, Canada. wdeitel@rogers.com.
Wayne
W
Deitel
Institute for Clinical Evaluative Sciences, Toronto, Canada. lawrence@ices.on.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. lawrence@ices.on.ca.|Department of Radiation Oncology, Sunnybrook Health Sciences Center, Toronto, Canada. lawrence@ices.on.ca.
Lawrence F
LF
Paszat
Institute for Clinical Evaluative Sciences, Toronto, Canada. drew.wilton@ices.on.ca.
Andrew S
AS
Wilton
Department of Surgery, Li Ki Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada. baxtern@smh.ca.|Institute for Clinical Evaluative Sciences, Toronto, Canada. baxtern@smh.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. baxtern@smh.ca.
Nancy N
NN
Baxter
D000328:Adult; D015331:Cohort Studies; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D009369:Neoplasms / Q000473:pathology*; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis*; D017741:Survivors; D055815:Young Adult