Table 4.

ORs for radiation exposure variables and breast cancer stratified by the number of variant genotypes in DSB repair genes

Exposure category0-1 variant*
2-4 variants*
Cases/controlsOR (95% CI)Cases/controlsOR (95% CI)
History of radiation to chest
    No943/834Reference882/840Reference
    Yes78/691.1 (0.8-1.6)80/561.4 (1.0-2.1)
LRT (P)0.24
No. chest X-rays§
    0202/142Reference190/142Reference
    1-5267/2630.7 (0.6-1.0)231/2570.7 (0.5-0.9)
    6-1094/790.9 (0.6-1.3)95/860.8 (0.6-1.3)
    ≥1166/421.1 (0.7-1.8)82/461.5 (0.9-2.3)
Ptrend0.890.27
LRT (P)0.51
No. mammograms§
    0137/93Reference87/80Reference
    1-282/681.0 (0.6-1.5)59/1170.5 (0.3-0.8)
    3-5138/1380.9 (0.6-1.3)128/1191.4 (0.9-2.2)
    6-10127/1230.9 (0.6-1.3)133/1041.7 (1.1-2.7)
    ≥11152/1061.1 (0.7-1.7)196/1162.2 (1.4-3.5)
Ptrend0.86<0.0001
LRT (P)<0.001
No. mammograms (2-y lag)§
    0172/113Reference114/99Reference
    1-2144/1121.0 (0.7-1.5)113/1510.8 (0.5-1.1)
    3-5107/1170.7 (0.5-1.0)116/1001.3 (0.8-1.9)
    6-10100/1020.7 (0.4-1.0)116/971.3 (0.9-2.1)
    ≥11114/850.9 (0.6-1.4)145/911.8 (1.2-2.8)
Ptrend0.160.0003
LRT (P)<0.001
No. mammograms at age <40 y§
    0471/396Reference412/401Reference
    153/570.8 (0.5-1.2)52/551.2 (0.8-1.8)
    ≥2106/741.1 (0.8-1.6)131/772.1 (1.5-3.0)
Ptrend0.80<0.0001
LRT (P)0.12
No. mammograms at age ≥40 y§
    0166/116Reference120/112Reference
    1-291/731.2 (0.8-1.8)70/1080.8 (0.5-1.2)
    3-5133/1300.9 (0.7-1.4)112/161.4 (0.9-2.1)
    6-10119/1140.9 (0.6-1.4)135/1031.9 (1.3-3.0)
    ≥11128/961.1 (0.7-1.7)168/992.4 (1.5-3.8)
Ptrend0.97<0.0001
LRT (P)<0.001
No. mammograms at age ≥40 y (2-y lag)§
    0225/150Reference178/140Reference
    1-2124/1061.0 (0.7-1.4)93/1310.7 (0.5-1.0)
    3-5105/1070.8 (0.5-1.1)106/991.1 (0.7-1.6)
    6-1086/940.7 (0.4-1.0)103/971.0 (0.7-1.6)
    ≥1197/720.9 (0.6-1.4)125/711.7 (1.1-2.7)
Ptrend0.130.02
LRT (P)0.004
  • * Variant genotypes: XRCC3 codon 241 any Met, NBS1 codon 185 any Gln, XRCC2 codon 188 any His, and BRCA2 codon 372 any His.

  • Adjusted for offsets, age, and race.

  • LRT for interaction between exposure and number of variant genotypes.

  • § Phase 2 (invasive and in situ) CBCS only.