Distribution (n, %) and MVOR estimates and 95% CIs for several hormone-related and nonhormone related risk factors and breast cancer characterized by ER+PR+ and ER−PR− subgroups among postmenopausal women
Note: the control group is the same for both ERPR subgroup analyses.
| Risk factor . | Controls . | . | ER+PR+ premenopausal cases . | . | . | . | ER−PR− premenopausal cases . | . | . | . | P b . | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | n . | (%) . | n . | (%) . | MVORa . | (95% CI) . | n . | (%) . | MVORa . | (95% CI) . | . | |||||||
| Age at menarche (yrs) | ||||||||||||||||||
| ≤11 | 431 | (18) | 255 | (19) | 1.00 | 102 | (23) | 1.00 | 0.24 | |||||||||
| 12 | 541 | (23) | 344 | (25) | 1.27 | (0.97–1.67) | 110 | (24) | 1.03 | (0.70–1.52) | ||||||||
| 13 | 651 | (27) | 392 | (29) | 1.18 | (0.90–1.54) | 109 | (24) | 0.96 | (0.65–1.42) | ||||||||
| ≥14 | 778 | (32) | 376 | (28) | 0.84 | (0.64–1.10) | 133 | (29) | 0.94 | (0.64–1.37) | ||||||||
| Parity | ||||||||||||||||||
| Nulliparousc | 275 | (11) | 195 | (14) | 1.00 | 63 | (13) | 1.00 | 0.84 | |||||||||
| 1 | 251 | (10) | 168 | (12) | 0.95 | (0.66–1.36) | 56 | (12) | 0.93 | (0.55–1.55) | ||||||||
| 2 | 716 | (29) | 436 | (31) | 0.84 | (0.61–1.15) | 137 | (30) | 0.73 | (0.46–1.15) | ||||||||
| ≥3 | 1196 | (49) | 594 | (43) | 0.71 | (0.53–0.97) | 206 | (45) | 0.72 | (0.46–1.12) | ||||||||
| Age at first live birth (yr) | ||||||||||||||||||
| 13–23 | 1216 | (50) | 590 | (43) | 1.00 | 207 | (45) | 1.00 | 0.50 | |||||||||
| 24–27 | 560 | (23) | 323 | (23) | 1.21 | (0.97–1.52) | 113 | (25) | 1.31 | (0.95–1.81) | ||||||||
| ≥28 | 367 | (15) | 275 | (20) | 1.64 | (1.28–2.10) | 77 | (17) | 1.30 | (0.89–1.89) | ||||||||
| Nulliparous | 273 | (11) | 195 | (14) | 1.46 | (1.08–1.97) | 63 | (12) | 1.46 | (0.95–2.26) | ||||||||
| Duration of OCd (yr) | ||||||||||||||||||
| Never or <1 | 1373 | (62) | 834 | (64) | 1.00 | 225 | (52) | 1.00 | 0.27 | |||||||||
| ≤4 | 313 | (14) | 174 | (13) | 0.85 | (0.65–1.11) | 72 | (17) | 1.04 | (0.71–1.53) | ||||||||
| 5–9 | 283 | (13) | 153 | (12) | 0.86 | (0.64–1.15) | 60 | (14) | 1.06 | (0.70–1.59) | ||||||||
| ≥10 | 259 | (12) | 149 | (11) | 0.95 | (0.71–1.27) | 72 | (17) | 1.41 | (0.96–2.08) | ||||||||
| Age at menopause (yr) | ||||||||||||||||||
| <45 | 812 | (35) | 389 | (29) | 1.00 | 141 | (32) | 1.00 | 0.32 | |||||||||
| 45–49 | 622 | (27) | 351 | (26) | 1.17 | (0.92–1.49) | 122 | (28) | 1.52 | (1.08–2.16) | ||||||||
| ≥50 | 890 | (38) | 601 | (45) | 1.50 | (1.19–1.88) | 174 | (40) | 1.63 | (1.15–2.30) | ||||||||
| Duration of HRTe use (yr) | ||||||||||||||||||
| Never or <1 | 1498 | (66) | 920 | (69) | 1.00 | 297 | (68) | 1.00 | 0.40 | |||||||||
| ≤2 | 280 | (12) | 130 | (10) | 0.77 | (0.57–1.03) | 56 | (13) | 0.89 | (0.60–1.32) | ||||||||
| 2–11 | 243 | (11) | 144 | (11) | 0.97 | (0.72–1.30) | 42 | (10) | 0.80 | (0.52–1.24) | ||||||||
| ≥12 | 247 | (11) | 131 | (10) | 0.94 | (0.67–1.31) | 42 | (10) | 1.26 | (0.79–2.01) | ||||||||
| BMI (kg/m2)f | ||||||||||||||||||
| 20–25 | 1008 | (42) | 489 | (36) | 1.00 | 172 | (38) | 1.00 | 0.29 | |||||||||
| <20 | 119 | (5) | 45 | (3) | 0.72 | (0.43–1.21) | 25 | (5) | 1.34 | (0.72–2.49) | ||||||||
| 25.1–27 | 392 | (16) | 208 | (15) | 1.10 | (0.84–1.43) | 72 | (16) | 1.09 | (0.74–1.61) | ||||||||
| >27 | 881 | (37) | 631 | (46) | 1.61 | (1.32–1.98) | 190 | (41) | 1.48 | (1.09–1.99) | ||||||||
| Alcohol (drinks/week)g | ||||||||||||||||||
| 0 | 766 | (33) | 435 | (33) | 1.00 | 144 | (33) | 1.00 | 0.89 | |||||||||
| ≤1 | 591 | (26) | 330 | (25) | 1.03 | (0.23–1.30) | 112 | (25) | 1.06 | (0.75–1.50) | ||||||||
| 1.5–3 | 483 | (21) | 256 | (19) | 0.90 | (0.69–1.15) | 93 | (21) | 0.90 | (0.62–1.32) | ||||||||
| ≥3.5 | 471 | (20) | 311 | (23) | 1.27 | (1.00–1.64) | 93 | (21) | 1.13 | (0.79–1.64) | ||||||||
| Cigarette smoking (pack-years) | ||||||||||||||||||
| 0 | 1287 | (56) | 693 | (52) | 1.00 | 210 | (48) | 1.00 | 0.07 | |||||||||
| 0.1–10 | 310 | (13) | 174 | (13) | 1.04 | (0.79–1.37) | 56 | (13) | 0.89 | (0.58–1.37) | ||||||||
| >10 | 714 | (31) | 459 | (35) | 1.16 | (0.94–1.42) | 175 | (40) | 1.53 | (1.15–2.04) | ||||||||
| Breast feeding (mos) | ||||||||||||||||||
| Never or nulliparous | 1178 | (50) | 705 | (52) | 1.00 | 237 | (52) | 1.00 | 0.64 | |||||||||
| 1–6 | 606 | (26) | 332 | (24) | 0.99 | (0.78–1.25) | 114 | (25) | 1.00 | (0.72–1.40) | ||||||||
| >6 | 595 | (25) | 332 | (24) | 0.92 | (0.73–1.16) | 107 | (23) | 1.09 | (0.77–1.52) | ||||||||
| Benign breast disease | ||||||||||||||||||
| No | 1784 | (77) | 598 | (48) | 1.00 | 215 | (52) | 1.00 | 0.06 | |||||||||
| Yes | 524 | (23) | 660 | (53) | 3.83 | (3.17–4.61) | 199 | (48) | 2.95 | (2.25–3.86) | ||||||||
| Family history breast cancerh | ||||||||||||||||||
| No | 1990 | (87) | 1089 | (81) | 1.00 | 374 | (85) | 1.00 | 0.64 | |||||||||
| Yes | 291 | (13) | 255 | (19) | 1.30 | (1.01–1.66) | 68 | (15) | 1.19 | (0.83–1.71) | ||||||||
| Age group (yr) | ||||||||||||||||||
| 25–49 | 222 | (9) | 140 | (10) | 77 | (17) | ||||||||||||
| 50–54 | 360 | (15) | 167 | (12) | 78 | (17) | ||||||||||||
| 55–59 | 459 | (19) | 270 | (19) | 90 | (19) | ||||||||||||
| 60–64 | 458 | (19) | 270 | (19) | 83 | (18) | ||||||||||||
| 65–69 | 522 | (21) | 305 | (22) | 80 | (17) | ||||||||||||
| 70–74 | 431 | (18) | 249 | (18) | 58 | (12) | ||||||||||||
| Risk factor . | Controls . | . | ER+PR+ premenopausal cases . | . | . | . | ER−PR− premenopausal cases . | . | . | . | P b . | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | n . | (%) . | n . | (%) . | MVORa . | (95% CI) . | n . | (%) . | MVORa . | (95% CI) . | . | |||||||
| Age at menarche (yrs) | ||||||||||||||||||
| ≤11 | 431 | (18) | 255 | (19) | 1.00 | 102 | (23) | 1.00 | 0.24 | |||||||||
| 12 | 541 | (23) | 344 | (25) | 1.27 | (0.97–1.67) | 110 | (24) | 1.03 | (0.70–1.52) | ||||||||
| 13 | 651 | (27) | 392 | (29) | 1.18 | (0.90–1.54) | 109 | (24) | 0.96 | (0.65–1.42) | ||||||||
| ≥14 | 778 | (32) | 376 | (28) | 0.84 | (0.64–1.10) | 133 | (29) | 0.94 | (0.64–1.37) | ||||||||
| Parity | ||||||||||||||||||
| Nulliparousc | 275 | (11) | 195 | (14) | 1.00 | 63 | (13) | 1.00 | 0.84 | |||||||||
| 1 | 251 | (10) | 168 | (12) | 0.95 | (0.66–1.36) | 56 | (12) | 0.93 | (0.55–1.55) | ||||||||
| 2 | 716 | (29) | 436 | (31) | 0.84 | (0.61–1.15) | 137 | (30) | 0.73 | (0.46–1.15) | ||||||||
| ≥3 | 1196 | (49) | 594 | (43) | 0.71 | (0.53–0.97) | 206 | (45) | 0.72 | (0.46–1.12) | ||||||||
| Age at first live birth (yr) | ||||||||||||||||||
| 13–23 | 1216 | (50) | 590 | (43) | 1.00 | 207 | (45) | 1.00 | 0.50 | |||||||||
| 24–27 | 560 | (23) | 323 | (23) | 1.21 | (0.97–1.52) | 113 | (25) | 1.31 | (0.95–1.81) | ||||||||
| ≥28 | 367 | (15) | 275 | (20) | 1.64 | (1.28–2.10) | 77 | (17) | 1.30 | (0.89–1.89) | ||||||||
| Nulliparous | 273 | (11) | 195 | (14) | 1.46 | (1.08–1.97) | 63 | (12) | 1.46 | (0.95–2.26) | ||||||||
| Duration of OCd (yr) | ||||||||||||||||||
| Never or <1 | 1373 | (62) | 834 | (64) | 1.00 | 225 | (52) | 1.00 | 0.27 | |||||||||
| ≤4 | 313 | (14) | 174 | (13) | 0.85 | (0.65–1.11) | 72 | (17) | 1.04 | (0.71–1.53) | ||||||||
| 5–9 | 283 | (13) | 153 | (12) | 0.86 | (0.64–1.15) | 60 | (14) | 1.06 | (0.70–1.59) | ||||||||
| ≥10 | 259 | (12) | 149 | (11) | 0.95 | (0.71–1.27) | 72 | (17) | 1.41 | (0.96–2.08) | ||||||||
| Age at menopause (yr) | ||||||||||||||||||
| <45 | 812 | (35) | 389 | (29) | 1.00 | 141 | (32) | 1.00 | 0.32 | |||||||||
| 45–49 | 622 | (27) | 351 | (26) | 1.17 | (0.92–1.49) | 122 | (28) | 1.52 | (1.08–2.16) | ||||||||
| ≥50 | 890 | (38) | 601 | (45) | 1.50 | (1.19–1.88) | 174 | (40) | 1.63 | (1.15–2.30) | ||||||||
| Duration of HRTe use (yr) | ||||||||||||||||||
| Never or <1 | 1498 | (66) | 920 | (69) | 1.00 | 297 | (68) | 1.00 | 0.40 | |||||||||
| ≤2 | 280 | (12) | 130 | (10) | 0.77 | (0.57–1.03) | 56 | (13) | 0.89 | (0.60–1.32) | ||||||||
| 2–11 | 243 | (11) | 144 | (11) | 0.97 | (0.72–1.30) | 42 | (10) | 0.80 | (0.52–1.24) | ||||||||
| ≥12 | 247 | (11) | 131 | (10) | 0.94 | (0.67–1.31) | 42 | (10) | 1.26 | (0.79–2.01) | ||||||||
| BMI (kg/m2)f | ||||||||||||||||||
| 20–25 | 1008 | (42) | 489 | (36) | 1.00 | 172 | (38) | 1.00 | 0.29 | |||||||||
| <20 | 119 | (5) | 45 | (3) | 0.72 | (0.43–1.21) | 25 | (5) | 1.34 | (0.72–2.49) | ||||||||
| 25.1–27 | 392 | (16) | 208 | (15) | 1.10 | (0.84–1.43) | 72 | (16) | 1.09 | (0.74–1.61) | ||||||||
| >27 | 881 | (37) | 631 | (46) | 1.61 | (1.32–1.98) | 190 | (41) | 1.48 | (1.09–1.99) | ||||||||
| Alcohol (drinks/week)g | ||||||||||||||||||
| 0 | 766 | (33) | 435 | (33) | 1.00 | 144 | (33) | 1.00 | 0.89 | |||||||||
| ≤1 | 591 | (26) | 330 | (25) | 1.03 | (0.23–1.30) | 112 | (25) | 1.06 | (0.75–1.50) | ||||||||
| 1.5–3 | 483 | (21) | 256 | (19) | 0.90 | (0.69–1.15) | 93 | (21) | 0.90 | (0.62–1.32) | ||||||||
| ≥3.5 | 471 | (20) | 311 | (23) | 1.27 | (1.00–1.64) | 93 | (21) | 1.13 | (0.79–1.64) | ||||||||
| Cigarette smoking (pack-years) | ||||||||||||||||||
| 0 | 1287 | (56) | 693 | (52) | 1.00 | 210 | (48) | 1.00 | 0.07 | |||||||||
| 0.1–10 | 310 | (13) | 174 | (13) | 1.04 | (0.79–1.37) | 56 | (13) | 0.89 | (0.58–1.37) | ||||||||
| >10 | 714 | (31) | 459 | (35) | 1.16 | (0.94–1.42) | 175 | (40) | 1.53 | (1.15–2.04) | ||||||||
| Breast feeding (mos) | ||||||||||||||||||
| Never or nulliparous | 1178 | (50) | 705 | (52) | 1.00 | 237 | (52) | 1.00 | 0.64 | |||||||||
| 1–6 | 606 | (26) | 332 | (24) | 0.99 | (0.78–1.25) | 114 | (25) | 1.00 | (0.72–1.40) | ||||||||
| >6 | 595 | (25) | 332 | (24) | 0.92 | (0.73–1.16) | 107 | (23) | 1.09 | (0.77–1.52) | ||||||||
| Benign breast disease | ||||||||||||||||||
| No | 1784 | (77) | 598 | (48) | 1.00 | 215 | (52) | 1.00 | 0.06 | |||||||||
| Yes | 524 | (23) | 660 | (53) | 3.83 | (3.17–4.61) | 199 | (48) | 2.95 | (2.25–3.86) | ||||||||
| Family history breast cancerh | ||||||||||||||||||
| No | 1990 | (87) | 1089 | (81) | 1.00 | 374 | (85) | 1.00 | 0.64 | |||||||||
| Yes | 291 | (13) | 255 | (19) | 1.30 | (1.01–1.66) | 68 | (15) | 1.19 | (0.83–1.71) | ||||||||
| Age group (yr) | ||||||||||||||||||
| 25–49 | 222 | (9) | 140 | (10) | 77 | (17) | ||||||||||||
| 50–54 | 360 | (15) | 167 | (12) | 78 | (17) | ||||||||||||
| 55–59 | 459 | (19) | 270 | (19) | 90 | (19) | ||||||||||||
| 60–64 | 458 | (19) | 270 | (19) | 83 | (18) | ||||||||||||
| 65–69 | 522 | (21) | 305 | (22) | 80 | (17) | ||||||||||||
| 70–74 | 431 | (18) | 249 | (18) | 58 | (12) | ||||||||||||
MVOR, model is adjusted for all other variables plus continuous age and oophorectomy.
P (likelihood ratio test) for heterogeneity in MVORs between ER−PR− and ER+PR+; calculated using polytomous logistic regression.
Includes both never pregnant and no live births.
OC, oral contraceptives.
HRT, includes both estrogen and estrogen/progestin regimens.
BMI was calculated using “weight 2 years ago” (prediagnosis).
Includes beer, wine, and liquor.
First degree relative.