Supplemental Table 1. Stratified Analysis between Internally-Weighted GRS and Breast Cancera

Internally-Weighted Genetic Risk Score
Continuous Scale / Tertile Scale
Tertile 1 / Tertile 2 / Tertile 3
OR (95% CI) / P-value / # cases / OR / # cases / OR (95% CI) / # cases / OR (95% CI)
Age at interview
<40 / 1.11 (0.99-1.15) / 0.071 / 65 / Ref. / 76 / 1.36 (0.84-2.19) / 74 / 1.28 (0.80-2.06)
40-49 / 0.96 (0.89-0.98) / 0.006 / 453 / Ref. / 435 / 0.87 (0.71-1.06) / 406 / 0.75 (0.61-0.91)
50-59 / 0.95 (0.89-1.01) / 0.102 / 273 / Ref. / 261 / 0.85 (0.66-1.10) / 252 / 0.80 (0.62-1.03)
≥60 / 1.00 (0.92-1.08) / 0.993 / 202 / Ref. / 188 / 1.06 (0.76-1.46) / 180 / 0.94 (0.68-1.30)
P-interaction / 0.95 / 0.98
Age at menarche
<14 / 0.95 (0.89-1.01) / 0.099 / 305 / Ref. / 309 / 0.83 (0.65-1.07) / 276 / 0.77 (0.60-1.00)
14-17 / 0.97 (0.93-1.02) / 0.264 / 562 / Ref. / 538 / 1.04 (0.87-1.25) / 531 / 0.88 (0.74-1.05)
≥17 / 0.99 (0.86-1.03) / 0.199 / 126 / Ref. / 113 / 0.70 (0.49-1.01) / 105 / 0.72 (0.49-1.04)
P-interaction / 0.47 / 0.53
Age at first live birth
<30 / 0.95 (0.92-0.99) / 0.008 / 813 / Ref. / 786 / 0.90 (0.77-1.04) / 733 / 0.80 (0.69-0.93)
≥30 / 1.03 (0.93-1.11) / 0.516 / 180 / Ref. / 174 / 1.12 (0.80-1.57) / 179 / 1.00 (0.72-1.39)
P-interaction / 0.51 / 0.89
Number of live births
0 / 1.04 (0.81-1.32) / 0.774 / 21 / Ref. / 27 / 1.47 (0.59-3.68) / 24 / 1.22 (0.49-3.05)
1-2 / 0.96 (0.92-0.99) / 0.023 / 838 / Ref. / 804 / 0.89 (0.77-1.03) / 759 / 0.81 (0.70-0.94)
≥3 / 1.00 (0.91-1.10) / 0.972 / 110 / Ref. / 107 / 1.27 (0.84-1.93) / 108 / 1.00 (0.67-1.49)
P-interaction / 0.71 / 0.72
Years of menstruation/reproduction
Tertile 1 (<28.46) / 0.99 (0.93-1.05) / 0.695 / 219 / Ref. / 226 / 0.95 (0.74-1.22) / 225 / 0.90 (0.70-1.16)
Tertile 2 (28.46-32.70) / 0.95 (0.89-1.00) / 0.071 / 258 / Ref. / 243 / 0.87 (0.68-1.12) / 218 / 0.80 (0.63-1.03)
Tertile 3(≥32.71) / 0.94 (0.88-0.99) / 0.042 / 309 / Ref. / 276 / 0.92 (0.72-1.19) / 262 / 0.76 (0.59-0.97)
P-interaction / 0.25 / 0.33
Oral contraceptive usage
No / 0.96 (0.92-0.99) / 0.023 / 637 / Ref. / 598 / 0.94 (0.80-1.10) / 561 / 0.81 (0.69-0.95)
Yes / 0.96 (0.89-1.05) / 0.376 / 151 / Ref. / 148 / 0.82 (0.59-1.12) / 145 / 0.85 (0.61-1.17)
P-interaction / 0.82 / 0.55
Menopausal Status
No / 0.95 (0.91-0.99) / 0.033 / 562 / Ref. / 555 / 0.90 (0.75-1.07) / 524 / 0.80 (0.67-0.96)
Yes / 0.98 (0.93-1.03) / 0.406 / 430 / Ref. / 404 / 0.96 (0.78-1.19) / 386 / 0.86 (0.70-1.06)
P-interaction / 0.50 / 0.84
Age at menopauseb
<48 / 0.94 (0.86-1.03) / 0.174 / 138 / Ref. / 141 / 0.81 (0.57-1.15) / 112 / 0.77 (0.54-1.11)
48-54 / 1.01 (0.95-1.08) / 0.667 / 273 / Ref. / 240 / 1.11 (0.84-1.46) / 257 / 0.96 (0.74-1.25)
≥55 / 0.77 (0.58-1.01) / 0.062 / 19 / Ref. / 23 / 0.83 (0.30-2.32) / 17 / 0.42 (0.15-1.21)
P-interaction / 0.72 / 0.53
Family history of breast cancer
No / 0.97 (0.93-1.00) / 0.056 / 938 / Ref. / 925 / 0.94 (0.82-1.08) / 873 / 0.84 (0.73-0.96)
Yes / 0.90 (0.76-1.07) / 0.255 / 55 / Ref. / 35 / 0.71 (0.34-1.49) / 29 / 0.71 (0.34-1.45)
P-interaction / 0.43 / 0.74
BMI
BMI<25 / 0.96 (0.92-1.00) / 0.037 / 655 / Ref. / 648 / 0.96 (0.81-1.13) / 586 / 0.78 (0.67-0.92)
BMI≥25 / 0.97 (0.92-1.03) / 0.386 / 338 / Ref. / 312 / 0.86 (0.67-1.10) / 326 / 0.94 (0.74-1.20)
P-interaction / 0.95 / 0.38
Physical activity
No / 0.96 (0.93-1.00) / 0.074 / 659 / Ref. / 645 / 0.89 (0.76-1.05) / 631 / 0.83 (0.71-0.98)
Yes / 0.96 (0.91-1.03) / 0.267 / 333 / Ref. / 315 / 1.00 (0.79-1.27) / 281 / 0.82 (0.65-1.05)
P-interaction / 0.98 / 0.65
ER Group
ER (-) / 0.93 (0.89-0.98) / 0.007 / 298 / Ref. / 284 / 0.91 (0.75-1.10) / 250 / 0.76 (0.62-0.92)
ER (+) / 0.97 (0.93-1.01) / 0.151 / 544 / Ref. / 513 / 0.91 (0.77-1.06) / 498 / 0.83 (0.71-0.97)
PR Group
PR (-) / 0.96 (0.92-1.00) / 0.082 / 333 / Ref. / 276 / 0.79 (0.66-0.96) / 300 / 0.82 (0.68-0.98)
PR (+) / 0.96 (0.92-1.00) / 0.054 / 501 / Ref. / 524 / 1.00 (0.85-1.18) / 446 / 0.80 (0.68-0.95)

Abbreviations: CI: confidence interval; OR: odds ratio

aModel adjusted for age at interview

bAmong postmenopausal women only