title: Patients with testicular cancer undergoing CT surveillance demonstrate a pitfall of radiation-induced cancer risk estimates: the timing paradox.
abstract: OBJECTIVE
  To demonstrate a limitation of lifetime radiation-induced cancer risk metrics in the setting of testicular cancer surveillance-in particular, their failure to capture the delayed timing of radiation-induced cancers over the course of a patient's lifetime.
  
  
  METHODS
  Institutional review board approval was obtained for the use of computed tomographic (CT) dosimetry data in this study. Informed consent was waived. This study was HIPAA compliant. A Markov model was developed to project outcomes in patients with testicular cancer who were undergoing CT surveillance in the decade after orchiectomy. To quantify effects of early versus delayed risks, life expectancy losses and lifetime mortality risks due to testicular cancer were compared with life expectancy losses and lifetime mortality risks due to radiation-induced cancers from CT. Projections of life expectancy loss, unlike lifetime risk estimates, account for the timing of risks over the course of a lifetime, which enabled evaluation of the described limitation of lifetime risk estimates. Markov chain Monte Carlo methods were used to estimate the uncertainty of the results.
  
  
  RESULTS
  As an example of evidence yielded, 33-year-old men with stage I seminoma who were undergoing CT surveillance were projected to incur a slightly higher lifetime mortality risk from testicular cancer (598 per 100 000; 95% uncertainty interval [UI]: 302, 894) than from radiation-induced cancers (505 per 100 000; 95% UI: 280, 730). However, life expectancy loss attributable to testicular cancer (83 days; 95% UI: 42, 124) was more than three times greater than life expectancy loss attributable to radiation-induced cancers (24 days; 95% UI: 13, 35). Trends were consistent across modeled scenarios.
  
  
  CONCLUSIONS
  Lifetime radiation risk estimates, when used for decision making, may overemphasize radiation-induced cancer risks relative to short-term health risks.
authors.affiliation: Massachusetts General Hospital Institute for Technology Assessment, Department of Radiology, 101 Merrimac St, 10th Floor, Boston, MA 02114, USA. pari@mgh-ita.org
authors.forename: Pari V
authors.initials: PV
authors.lastname: Pandharipande
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Eisenberg
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lee
authors.forename: Michael E
authors.initials: ME
authors.lastname: Gilmore
authors.forename: Ekin A
authors.initials: EA
authors.lastname: Turan
authors.forename: Sarabjeet
authors.initials: S
authors.lastname: Singh
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
authors.forename: Bob
authors.initials: B
authors.lastname: Liu
authors.forename: Chung Yin
authors.initials: CY
authors.lastname: Kong
authors.forename: G Scott
authors.initials: GS
authors.lastname: Gazelle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001900:Boston / Q000453:epidemiology; D015897:Comorbidity; D006801:Humans; D015994:Incidence; D008017:Life Expectancy; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000401:mortality*; D011159:Population Surveillance; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D013736:Testicular Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality*; D014057:Tomography, X-Ray Computed / Q000401:mortality* / Q000706:statistics & numerical data