Table 4.
Effect of lifetime chest X-ray exposure (any exposure) on breast cancer risk according to the number of exposures, the age at first exposure, and the first full-term pregnancy
| Number of | Multiple Imputation | |||||
|---|---|---|---|---|---|---|
| Cases | Controls | ORa | 95% CI | ORa | 95% CI | |
| Chest X-ray exposureb | ||||||
| Never | 208 | 239 | 1 | 1 | ||
| Ever | 1304 | 1104 | 2.05 | 1.55–2.73 | 2.05 | 1.54–2.72 |
| Number of exposures | ||||||
| 0 | 208 | 239 | 1 | 1 | ||
| 1–3 | 392 | 390 | 1.70 | 1.23–2.34 | 1.62 | 1.18–2.23 |
| 4–9 | 251 | 200 | 2.52 | 1.76–3.61 | 2.29 | 1.65–3.16 |
| ≥10 | 263 | 215 | 2.37 | 1.64–3.43 | 2.70 | 1.89–3.87 |
| Continuous | 1.03 | 1.01–1.04 | 1.03 | 1.02–1.05 | ||
| Age at first exposure, yearsc | ||||||
| No exposure | 208 | 239 | 0.55 | 0.40–0.76 | 0.58 | 0.42–0.80 |
| ≥20 | 485 | 490 | 1 | 1 | ||
| 15–19 | 288 | 222 | 1.02 | 0.75–1.37 | 1.01 | 0.75–1.36 |
| <15 | 290 | 219 | 1.11 | 0.83–1.50 | 1.08 | 0.80–1.45 |
| Continuous | 1.00 | 0.99–1.01 | 1.01 | 0.99–1.02 | ||
| According to first full-term pregnancy (FFTP)c | ||||||
| Only after FFTPd | 268 | 232 | 1 | 1 | ||
| Before (incl. no FTP) | 825 | 725 | 0.81 | 0.61–1.08 | 0.85 | 0.64–1.12 |
| According to first FFTP and number of exposures | ||||||
| Only after and ≤5d | 186 | 178 | 1 | 1 | ||
| Only after and >5d | 56 | 43 | 1.77 | 0.98–3.18 | 1.68 | 0.99–2.85 |
| Before and ≤5 (incl. no FTP) | 442 | 412 | 0.95 | 0.67–1.36 | 0.89 | 0.63–1.25 |
| Before and >5 (incl. no FTP) | 272 | 215 | 1.12 | 0.77–1.61 | 1.33 | 0.96–1.85 |
Abbreviations: OR (95%CI) odds ratio (95% confidence interval)
aAdjusted for age at censoring, birth cohort (≤1945; 1946–1959; ≥1960), number of full-term pregnancies (>2; 1–2; 0), mammography use (never; ever), educational level (intermediate/high; basic; not graduated), BMI (18.5–24.9; <18.5; ≥25 and <30; ≥30), smoking (no; current; past), and breast cancer family history (0;1st degree; 2nd degree)
bChest X-ray exposure includes pulmonary radiological examinations in the field of preventive/occupational medicine or for lung disease, preoperative radiological examinations, and radiological examinations of heart and thoracic vessels for all the reported procedures
cAdjusted as in a plus number of exposures (≤5;>5)
dAfter = also includes chest X-ray exposure that occurred during the same year of first full-term pregnancy