Table 3.
Luminal A n = 571 | HER2+ n = 225 | TNBC n = 159 | |||
---|---|---|---|---|---|
| |||||
No. (%) | No. (%) | OR (95% CI) | No. (%) | OR (95% CI) | |
| |||||
Age at diagnosis, y | |||||
< 50 | 250 (43.8) | 93 (41.3) | 1.00 | 93 (58.5) | 1.00 |
50 to 59 | 169 (29.6) | 73 (32.4) | 1.17 (0.81–1.68) | 30 (18.9) | 0.44 (0.28–0.70) |
≥ 60 | 152 (26.6) | 59 (26.2) | 1.05 (0.71–1.56) | 36 (22.6) | 0.57 (0.36–0.88) |
Per 5 y | 1.01 (0.95–1.08) | 0.89 (0.83–0.96) | |||
Age at menarche, y | |||||
< 13 | 261 (45.7) | 104 (46.2) | 1.00 | 64 (40.5) | 1.00 |
≥ 13 | 310 (54.3) | 121 (53.8) | 0.98 (0.71–1.33) | 94 (59.5) | 1.27 (0.88–1.82) |
Per 5 y | 0.93 (0.58–1.50) | 1.64 (0.95–2.82) | |||
Parity | |||||
Nulliparous | 58 (10.2) | 25 (11.1) | 1.02 (0.59–1.75) | 9 (5.66) | 0.71 (0.32–1.57) |
1 to 2 children | 176 (30.8) | 74 (32.9) | 1.00 | 39 (24.5) | 1.00 |
≥ 3 children | 337 (59.0) | 126 (56.0) | 0.87 (0.61–1.24) | 111 (69.8) | 1.68 (1.10–2.55) |
Per birth (excludes nulliparous) | 0.99 (0.91–1.08) | 1.07 (0.98–1.18) | |||
Age at first full-term pregnancy, y | |||||
< 21 | 201 (39.2) | 77 (38.5) | 1.00 | 68 (45.6) | 1.00 |
21–24 | 133 (25.9) | 55 (27.5) | 1.08 (0.72–1.63) | 42 (28.2) | 0.90 (0.58–1.41) |
≥ 25 | 179 (34.9) | 68 (34.0) | 0.99 (0.68–1.46) | 39 (26.2) | 0.61 (0.39–0.95) |
Per 5 y | 1.00 (0.97–1.03) | 0.95 (0.92–0.99) | |||
Time since last full-term pregnancyb, y | |||||
> 10 | 159 (64.4) | 53 (57.0) | 1.00 | 48 (60.0) | 1.00 |
≤ 10 | 88 (35.6) | 40 (43.0) | 1.83 (0.96–3.48) | 32 (40.0) | 0.76 (0.38–1.52) |
Per 5 y | 0.97 (0.78–1.21) | 0.99 (0.78–1.26) | |||
Lifetime duration of breastfeedingc, mo | |||||
Never | 134 (26.1) | 58 (29.0) | 1.00 | 23 (15.3) | 1.00 |
Up to 12 | 188 (36.7) | 63 (31.5) | 0.77 (0.50–1.18) | 52 (34.7) | 1.44 (0.83–2.49) |
> 12 | 191 (37.2) | 79 (39.5) | 0.97 (0.63–1.50) | 75 (50.0) | 2.14 (1.24–3.68) |
Per 6 mo | 1.03 (0.99–1.06) | 1.04 (1.01–1.08) | |||
Breastfeeding duration per birthc, mo | |||||
Never | 134 (26.1) | 58 (29.0) | 1.00 | 23 (15.3) | 1.00 |
> 0 to 5 | 206 (40.2) | 66 (33.0) | 0.74 (0.49–1.13) | 60 (40.0) | 1.52 (0.89–2.60) |
> 5 | 173 (33.7) | 76 (38.0) | 1.03 (0.67–1.59) | 67 (44.7) | 2.07 (1.20–3.58) |
Per 6 mo | 1.06 (0.91–1.24) | 1.20 (1.03–1.41) | |||
Time from menarche to first pregnancy, y | |||||
< 8 | 179 (34.9) | 71 (35.5) | 1.00 | 69 (46.6) | 1.00 |
8–12 | 172 (33.5) | 68 (34.0) | 1.00 (0.67–1.48) | 49 (33.1) | 0.75 (0.49–1.15) |
≥ 13 | 162 (31.6) | 61 (30.5) | 0.95 (0.63–1.42) | 30 (20.3) | 0.47 (0.29–0.77) |
Per 10 y | 0.99 (0.85–1.14) | 0.78 (0.65–0.93) | |||
Duration of menstruationd, y | |||||
7.6–27.35 | 172 (32.4) | 59 (28.8) | 1.00 | 64 (42.4) | 1.00 |
27.4–33.45 | 174 (32.8) | 62 (30.2) | 1.04 (0.68–1.59) | 60 (39.7) | 0.99 (0.65–1.53) |
33.5–50.5 | 185 (34.8) | 84 (41.0) | 1.33 (0.87–2.03) | 27 (17.9) | 0.43 (0.25–0.74) |
Per 5 y | 1.09 (0.95–1.24) | 0.79 (0.69–0.91) | |||
Duration of menstruatione, y | |||||
0–25.23 | 150 (31.5) | 56 (30.8) | 1.00 | 58 (40.9) | 1.00 |
25.25–31.75 | 160 (33.6) | 55 (30.2) | 0.92 (0.60–1.43) | 57 (40.1) | 0.96 (0.62–1.49) |
31.85–50.5 | 166 (34.9) | 71 (39.0) | 1.15 (0.75–1.78) | 27 (19.0) | 0.47 (0.28–0.79) |
Per 5 y | 1.04 (0.92–1.18) | 0.82 (0.72–0.93) | |||
Age at menopause, y | |||||
< 50 | 164 (57.1) | 68 (58.6) | 1.00 | 48 (68.6) | 1.00 |
≥ 50 | 123 (42.9) | 48 (41.4) | 0.97 (0.62–1.52) | 22 (31.4) | 0.59 (0.33–1.04) |
Per 5 y | 1.07 (0.90–1.27) | 0.82 (0.67–1.01) | |||
Hormone replacement therapy | |||||
Never | 490 (86.9) | 192 (85.7) | 1.00 | 142 (89.3) | 1.00 |
Ever | 74 (13.1) | 32 (14.3) | 1.09 (0.69–1.72) | 17 (10.7) | 0.99 (0.56–1.77) |
Hormone contraceptive use | |||||
Never | 244 (42.8) | 102 (45.3) | 1.00 | 78 (49.1) | 1.00 |
Ever | 326 (57.2) | 123 (54.7) | 0.91 (0.66–1.26) | 81 (50.9) | 0.70 (0.49–1.01) |
Abbreviations: CI, confidence interval; HER2, human epidermal growth factor receptor 2; OR, odds ratio; TNBC, triple negative breast cancer.
Adjusted for age at diagnosis (continuous) and country (U.S. vs. Mexico).
Among pre-menopausal women only.
Excludes nulliparous women.
Tertile categories; duration accounts for pregnancy. Excludes 62 women never having a regular period and 13 women with unknown age at menopause or menopausal status.
Tertile categories; duration accounts for pregnancy and breastfeeding. Excludes 62 women never having a regular period, 13 women with unknown age at menopause/menopausal status, and 99 women with unknown lifetime duration breastfeeding.