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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

From: Diagnostic chest X-rays and breast cancer risk among women with a hereditary predisposition to breast cancer unexplained by a BRCA1 or BRCA2 mutation

  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
  1. Abbreviations: OR (95%CI) odds ratio (95% confidence interval)
  2. 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)
  3. 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
  4. cAdjusted as in plus number of exposures (≤5;>5)
  5. dAfter = also includes chest X-ray exposure that occurred during the same year of first full-term pregnancy