Table 2 The association between hyperthyroidism and major breast cancer risk predictors in KARMA cohort (N = 67,518)
From: Hyperthyroidism is associated with breast cancer risk and mammographic and genetic risk predictors
Variable names | No. of non-hyperthyroidism | No. of hyperthyroidism | OR1 (95% CI) | OR2 (95% CI) |
|---|---|---|---|---|
Benign breast disease | ||||
 No | 47,345 | 451 | 1.00 (REF) | 1.00 (REF) |
 Yes | 13,820 | 135 | 1.03 (0.85–1.24) | 1.01 (0.83–1.22) |
Number of births | ||||
 0 | 7836 | 78 | 1.00 (REF) | 1.00 (REF) |
 1 | 9032 | 96 | 1.07 (0.79–1.44) | 1.07 (0.79–1.45) |
 2 | 29,471 | 296 | 1.01 (0.79–1.30) | 1.03 (0.80–1.33) |
 > 2 | 15,245 | 130 | 0.86 (0.65–1.14) | 0.86 (0.65–1.14) |
Age at first birth*(years) | ||||
 < 25 | 18,167 | 206 | 1.00 (REF) | 1.00 (REF) |
 25–29 | 19,023 | 161 | 0.75 (0.61–0.92) | 0.78 (0.63–0.97) |
 ≥ 30 | 16,536 | 155 | 0.83 (0.67–1.02) | 0.90 (0.71–1.14) |
Breastfeeding duration* (months) | ||||
  < 1 | 4557 | 60 | 1.00 (REF) | 1.00 (REF) |
 1–6 | 19,276 | 210 | 0.83 (0.62–1.10) | 0.86 (0.64–1.15) |
  > 6 | 29,220 | 249 | 0.65 (0.49–0.86) | 0.73 (0.54–0.98) |
BMI (kg/cm2) category | ||||
 < 18.5 | 639 | 6 | 1.03 (0.46–2.32) | 1.03 (0.46–2.33) |
 18.5–25 | 34,076 | 310 | 1.00 (REF) | 1.00 (REF) |
 25–30 | 19,518 | 188 | 1.06 (0.88–1.27) | 1.03 (0.86–1.24) |
 > 30 | 7974 | 96 | 1.32 (1.05–1.67) | 1.28 (1.01–1.61) |
Family history of breast cancer | ||||
 No | 51,994 | 495 | 1.00 (REF) | 1.00 (REF) |
 Yes | 7809 | 77 | 1.04 (0.81–1.32) | 1.02 (0.80–1.30) |
Oral contraceptive use | ||||
 No | 12,162 | 128 | 1.00 (REF) | 1.00 (REF) |
 Yes | 49,271 | 471 | 0.91 (0.75–1.11) | 0.95 (0.78–1.16) |
Hormone replacement therapy use | ||||
 No | 43,867 | 414 | 1.00 (REF) | 1.00 (REF) |
 Yes | 17,269 | 180 | 1.10 (0.93–1.32) | 0.99 (0.82–1.20) |
Age at menarche (years) | ||||
 < 12 | 20,998 | 217 | 1.00 (REF) | 1.00 (REF) |
 13–16 | 36,565 | 345 | 0.91 (0.77–1.08) | 0.92 (0.77–1.09) |
 > 16 | 2966 | 30 | 0.98 (0.67–1.44) | 0.97 (0.66–1.43) |
Menopausal status | ||||
 Pre-menopausal | 27,283 | 225 | 1.00 (REF) | 1.00 (REF) |
 Peri-menopausal | 3753 | 40 | 1.29 (0.92–1.81) | 1.29 (0.90–1.86) |
 Post-menopausal | 35,830 | 387 | 1.31 (1.11–1.54) | 1.36 (1.02–1.81) |
History of irregular menstrual periods | ||||
 No | 53,603 | 520 | 1.00 (REF) | 1.00 (REF) |
 Yes | 7113 | 75 | 1.09 (0.85–1.39) | 1.11 (0.87–1.42) |