Table 4.
Odds ratios for breast cancer risk, by estimated total radiation dose to the breast from the Chernobyl accident, among female residents of Bryansk Oblast, October 2008 to February 2013
| Dose octilea | Mean (min – max) dose, cGy | No. (%) of cases (n = 468) | No. (%) of controls (n = 468) | Odds Ratiob (95% CI) |
|
|---|---|---|---|---|---|
| Unadjusted | Adjusted | ||||
| 1 | 0.08 (0.04–0.10) | 57 (12) | 60 (13) | 1.0 | 1.0 |
| 2 | 0.12 (0.10–0.13) | 54 (12) | 63 (13) | 0.9 (0.5, 1.5) | 0.9 (0.5, 1.6) |
| 3 | 0.15 (0.13–0.17) | 59 (13) | 58 (12) | 1.1 (0.6, 1.9) | 1.2 (0.7, 2.1) |
| 4 | 0.20 (0.17–0.25) | 56 (12) | 61 (13) | 1.0 (0.6, 1.8) | 1.2 (0.6, 2.2) |
| 5 | 0.32 (0.25–0.41) | 58 (12) | 59 (13) | 1.2 (0.7, 2.2) | 1.1 (0.6, 2.0) |
| 6 | 0.56 (0.41–0.76) | 61 (13) | 56 (12) | 1.6 (0.8, 3.3) | 1.9 (0.9, 3.8) |
| 7 | 1.86 (0.79–3.57) | 64 (14) | 53 (11) | 2.4 (1.1, 5.6) | 3.0 (1.3, 7.0) |
| 8 | 7.28 (3.61–41.5) | 59 (13) | 58 (12) | 2.3 (0.9, 5.8) | 2.7 (1.0, 7.3) |
Octiles of estimated breast dose were calculated for all 936 cases and controls combined.
Odds ratios were estimated by conditional logistic regression, to account for individual matching on birth year and raion and type of settlement ATA, in a univariable model (‘Unadjusted’), or in a multivariable model (‘Adjusted’) that included the following covariates: menopausal status at diagnosis/reference date (premenopausal vs natural menopause vs other menopause), history of breast cancer in first degree relative (yes vs no), nulliparity (yes vs no), age at first live birth, subject’s education level (≤grade 11 vs technical school vs college/university) and history of employment in metallurgy or mining (yes vs no). The ‘Adjusted’ model excluded three case–control pairs in which menopausal status was unknown for one case or control. ATA, at the time of the Chernobyl accident (April 26, 1986); cGy, centigray; CI, confidence interval.