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Table 2 Adjusted ORs for breast cancer associated with hormone-related risk factors by ER/PR status

From: Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a case–control and a case–case comparison

Variables No. controls All cases versus controls ER+PR+ cases versus controls ER- PR- cases versus controls ER+PR+ cases versus ER- PR- cases
   Number of cases OR (95% CI) Number of cases OR (95% CI) Number of cases OR (95% CI) OR (95% CI)
Age at menarche, years
   ≤ 11 90 400 1.00 188 1.00 92 1.00 1.00
   12 109 532 1.13 (0.83–1.55) 278 1.24 (0.88–1.75) 119 1.18 (0.79–1.77) 1.04 (0.74–1.47)
   13 121 475 0.88 (0.65–1.21) 231 0.87 (0.62–1.24) 110 0.94 (0.62–1.41) 0.93 (0.65–1.33)
   ≥ 14 120 318 0.61 (0.44–0.85) 157 0.60 (0.42–0.86) 64 0.59 (0.38–0.92) 1.02 (0.67–1.53)
   Trend p value    0.0007   0.0006   0.008 0.85
Number of full-term pregnanciesa
   None 125 564 1.00 301 1.00 113 1.00 1.00
   1 85 347 0.91 (0.66–1.25) 157 0.77 (0.55–1.10) 82 1.06 (0.70–1.62) 0.70 (0.49–1.02)
   2 139 492 0.81 (0.61–1.07) 251 0.77 (0.57–1.06) 106 0.95 (0.64–1.39) 0.84 (0.60–1.18)
   3 56 224 0.81 (0.56–1.18) 100 0.69 (0.45–1.04) 54 1.06 (0.65–1.73) 0.68 (0.44–1.05)
   ≥ 4 35 98 0.49 (0.31–0.78) 45 0.47 (0.28–0.80) 30 0.72 (0.39–1.33) 0.65 (0.37–1.15)
   Trend p value    0.008   0.005   0.50 0.09
Age at first full-term pregnancy for parous women, yearsa,b
   <22 68 316 1.00 126 1.00 96 1.00 1.00
   22–27 89 333 1.07 (0.72–1.58) 149 1.14 (0.73–1.78) 81 0.92 (0.56–1.50) 1.25 (0.81–1.94)
   28–31 78 265 1.03 (0.66–1.60) 134 1.17 (0.71–1.93) 57 0.82 (0.46–1.45) 1.42 (0.85–2.37)
   ≥ 32 80 247 0.92 (0.57–1.48) 144 1.23 (0.72–2.10) 38 0.56 (0.30–1.07) 2.22 (1.24–3.98)
   Trend p value    0.65   0.49   0.08 0.009
Duration of breastfeeding for parous women, monthsa,b
   0 38 247 1.00 102 1.00 63 1.00 1.00
   <1 23 144 0.99 (0.56–1.77) 65 1.01 (0.53–1.90) 38 1.19 (0.59–2.39) 0.82 (0.47–1.44)
   1–6 80 273 0.58 (0.37–0.91) 131 0.57 (0.34–0.94) 68 0.72 (0.41–1.27) 0.77 (0.47–1.26)
   7–23 110 322 0.52 (0.33–0.82) 165 0.52 (0.31–0.87) 63 0.55 (0.31–0.98) 0.97 (0.59–1.61)
   ≥ 24 64 175 0.51 (0.30–0.86) 90 0.49 (0.27–0.87) 40 0.62 (0.32–1.21) 0.77 (0.42–1.39)
   Trend p value    0.001   0.002   0.03 0.63
BMI 1 year before reference date, kg/m2
   <25 257 939 1.00 495 1.00 183 1.00 1.00
   25–29 95 425 1.18 (0.89–1.55) 209 1.11 (0.82–1.50) 101 1.41 (0.99–2.02) 0.81 (0.59–1.10)
   30–34 51 221 1.01 (0.70–1.44) 94 0.88 (0.59–1.30) 61 1.43 (0.91–2.23) 0.60 (0.40–0.89)
   ≥ 35 37 140 0.88 (0.58–1.34) 56 0.69 (0.43–1.11) 40 1.18 (0.70–2.01) 0.61 (0.38–0.99)
   Trend p value    0.82   0.20   0.16 0.005
Duration of COC use, years
   Never 47 244 1.00 128 1.00 47 1.00 1.00
   <1 73 295 0.78 (0.51–1.18) 133 0.70 (0.44–1.12) 59 0.76 (0.43–1.33) 0.93 (0.57–1.52)
   1–4 108 429 0.80 (0.54–1.19) 227 0.81 (0.53–1.25) 90 0.87 (0.52–1.46) 0.92 (0.59–1.43)
   5–9 115 362 0.62 (0.42–0.93) 173 0.57 (0.37–0.88) 90 0.82 (0.49–1.37) 0.71 (0.45–1.12)
   ≥ 10 97 395 0.84 (0.56–1.26) 193 0.76 (0.49–1.18) 99 1.27 (0.75–2.14) 0.61 (0.39–0.96)
   Trend p value    0.30   0.16   0.18 0.008
Alcohol drinking status during reference agec
   Never 141 558 1.00 251 1.00 138 1.00 1.00
   Former 90 328 0.96 (0.71–1.31) 162 1.02 (0.72–1.44) 74 0.88 (0.59–1.33) 1.14 (0.79–1.64)
   Current 209 839 1.05 (0.81–1.36) 441 1.17 (0.88–1.55) 173 0.93 (0.67–1.30) 1.25 (0.93–1.68)
Average number of alcoholic drinks per week in recent 5 years
   Never 141 558 1.00 251 1.00 138 1.00 1.00
   <3 130 481 1.01 (0.76–1.35) 248 1.11 (0.81–1.53) 101 0.89 (0.61–1.30) 1.22 (0.87–1.71)
   3–5 49 171 0.93 (0.63–1.37) 90 1.01 (0.66–1.54) 34 0.76 (0.45–1.28) 1.31 (0.81–2.11)
   6–11 32 157 1.16 (0.75–1.81) 82 1.26 (0.78–2.03) 34 1.06 (0.60–1.86) 1.20 (0.74–1.94)
   > 12 17 127 1.77 (1.01–3.08) 68 2.10 (1.17–3.79) 27 1.71 (0.87–3.38) 1.24 (0.73–2.09)
   Trend p value    0.12   0.03   0.42 0.23
Drinking alcohol but not in the recent five years 71 231 0.88 (0.63–1.22) 115 0.92 (0.63–1.34) 51 0.80 (0.51–1.26) 1.14 (0.76–1.73)
  1. ORs are from multivariable unconditional logistic regression models with the adjustment for race, age, education, first-degree breast cancer family history, age at menarche, gravidity, number of full-term pregnancies, BMI 1 year before reference date, COC use, the average number of alcoholic drinks per week in the recent 5 years, a variable combining menopausal status and hormone therapy use except where otherwise noted. BMI, body mass index; COC, combined oral contraceptive; CI, confidence interval; ER, estrogen receptor; OR, odds ratio; PR, progesterone receptor. aModels did not include gravidity. bAge at first full-term pregnancy and duration of breastfeeding mutually adjusted for each other. cAlcohol drinking status during reference age replaced the number of alcoholic drinks per week in the recent 5 years in the models.