Table 4.

Analysis of radiation dose-response by exposure received in time windows defined by reproductive events to reflect stages of breast tissue development

ModelBreast development windown (%) any dose*Mean dose Dkx in selected window (cGy)ERR/Gy in specified window Dx (95% CI)Deviance difference (df), P-value
ReferenceAll windows combined2,971 (100)11.63.30 (0.13-9.63)
Window 1Before breast budding690 (23)1.7−0.24§2.02 (3 df), P = 0.57
Window 2Between budding and menarche1,215 (41)2.71.73§
Window 3Between menarche and giving birth to first child2,312 (78)7.115.94§
Window 4After giving birth to first child258 (9)0.14.36§
  • NOTE: Excludes n = 31 subjects with missing data on age at menarche or age at first birth; includes 117,039 person-years and 76 cases.

  • * Percentage of total number of scoliosis patients (n = 3,010) who had any dose to the breast in the respective time window.

  • Window doses are not time dependent; the dose in all windows combined is the sum of the four window doses as used in these analyses.

  • Likelihood ratio test for improvement in model fit when the window-specific doses are given separately.

  • § Likelihood-based confidence limits could not be calculated.