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Key Dates

  • March 6, 2012 – Online Registration Opens

  • March 12, 2012 – Abstract submission Closes (all abstracts due at this time)

  • March 12, 2012 - New Investigator Award Applications Due

  • April 16, 2012 - Accepted abstracts for Poster Session, New Investigators Announced

  • May 4, 2012 - Hotel Reservations Close

  • May 21, 2012 - Online Registration Closes
Effect of dose uncertainty on estimated threshold of skin cancer dose-response in the Radiation Effects Research Foundation Life Span Study cohort

Harry M Cullings, Radiation Effects Research Foundation 
*Munechika Misumi, Radiation Effects Research Foundation 
Kotaro Ozasa, Department of Epidemiology, Radiation Effects Research Foundation 
Hiromi Sugiyama, Department of Epidemiology, Radiation Effects Research Foundation 

Keywords: Skin cancer, threshold, dose uncertainty

We investigated the impact of uncertainty in the radiation dose estimates on the dose-response of basal cell carcinoma (BCC) among atomic-bomb survivors. We presented previously that the existence of a threshold was suggested in the analysis of radiation dose-response of BCC. We conducted sensitivity analyses of the threshold assuming several scenarios of dose error. At the Radiation Effects Research Foundation (RERF), so-called classical-type measurement error is taken into consideration by a regression calibration in the analysis of epidemiological studies. However, Berkson error has received less attention despite the fact that RERF collected detailed shielding histories only from proximal survivors exposed within 1600m and 2000m from the hypocenters of Hiroshima and Nagasaki, respectively, at the time of bombing, and averaged transmission factors of shielding are assigned to subjects who lack a detailed shielding history, in calculating radiation dose estimates based on the DS02 dosimetry system. Also, multiplicative measurement error models are common for radiation dose error. It is well known that the risk can be overestimated for a multiplicative error model with Berkson error. We assumed heterogeneous Berkson errors for subjects with and without detailed shielding information, in addition to 35% classical error, and obtained a specific correction factor for each subject. Study subjects were 80,158 of 120,321 atomic bomb survivors in the Life Span Study (LSS) cohort who were in Hiroshima or Nagasaki at the time of the bombing and had a radiation dose estimated using the DS02 dosimetry system. When we assumed 20% Berkson error for proximal survivors and 40% Berkson error for non-proximal survivors, the best-fitting model estimated a dose threshold of 0.7 Gy (95% CI = 0.35–0.95), which was about the same as our previous report. This result is still preliminary and full results will be presented in the session.