Table 3.
Relationship between risk factors and breast cancer risk among postmenopausal non-Hispanic Whites and US Hispanics according to percent Native American ancestry
| Risk Factors | Non-Hispanic White | US Hispanic | Pinteraction | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 0–43% Native American Ancestry | 43.1%–100% Native American Ancestry | |||||||||
|
|
|
|
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| Cases (n = 875) | Controls (n=979) | OR (95% CI)a | Cases (n =332) | Controls (n = 369) | OR (95% CI)a | Cases (n = 282) | Controls (n = 416) | OR (95% CI)a | ||
| Ageb, y | 0.98 (0.97, 0.99) | 1.01 (0.99, 1.02) | 1.00 (0.98, 1.02) | 0.20 | ||||||
| Family history of breast cancer, No. (%) | 0.93 | |||||||||
| Yes | 201 (23.0) | 162 (16.6) | 1.57 (1.24, 1.99) | 76 (22.9) | 53 (14.4) | 1.82 (1.22, 2.73) | 45 (16.0) | 49 (11.8) | 1.61 (1.01, 2.55) | |
| No | 674 (77.0) | 817 (83.4) | Referent | 256 (77.1) | 316 (85.6) | Referent | 237 (84.0) | 367 (88.2) | Referent | |
| No. births and age at first birthc, No. (%) | 0.76 | |||||||||
| Nulliparous | 126 (14.4) | 125 (12.8) | 1.00 (0.72, 1.40) | 25 (7.5) | 28 (7.6) | 0.89 (0.47, 1.68) | 30 (10.6) | 20 (4.8) | 2.10 (1.07, 4.12) | |
| 1–2, <25 y | 186 (21.3) | 192 (19.6) | 1.13 (0.68, 1.48) | 62 (18.7) | 56 (15.2) | 1.30 (0.82, 2.07) | 48 (17.0) | 49 (11.8) | 1.60 (0.98, 2.62) | |
| 1–2, ≥25 y | 172 (19.7) | 171 (17.5) | 1.14 (0.87, 1.50) | 61 (18.4) | 58 (15.7) | 1.24 (0.79, 1.95) | 36 (12.8) | 47 (11.3) | 1.15 (0.69, 1.93) | |
| ≥3, <25 y | 305 (34.9) | 378 (38.6) | Referent | 143 (43.1) | 184 (49.9) | Referent | 143 (50.7) | 237 (57.0) | Referent | |
| ≥3, ≥25 y | 86 (9.8) | 113 (11.5) | 0.99 (0.71, 1.37) | 41 (12.4) | 43 (11.7) | 1.14 (0.69, 1.89) | 25 (8.9) | 63 (15.1) | 0.67 (0.40, 1.14) | |
| Breastfeedingd, mos, No. (%) | 0.31 | |||||||||
| None | 416 (47.5) | 409 (41.8) | 1.11 (0.84, 1.46) | 159 (47.9) | 147 (39.8) | 1.42 (0.95, 2.12) | 135 (47.9) | 146 (35.1) | 1.43 (0.94, 2.17) | |
| ≤12 | 272 (31.1) | 356 (36.1) | 0.86 (0.66, 1.12) | 96 (28.9) | 117 (32.3) | 0.95 (0.62, 1.46) | 73 (25.9) | 124 (29.8) | 1.03 (0.67, 1.58) | |
| >12 | 187 (21.4) | 214 (21.9) | Referent | 77 (23.2) | 103 (27.9) | Referent | 74 (26.2) | 146 (35.1) | Referent | |
| Ptrend = 0.31 | Ptrend = 0.06 | Ptrend = 0.09 | ||||||||
| Body mass indexb, kg/m2, No. (%) | 0.76 | |||||||||
| <25.0 | 347 (39.7) | 397 (40.6) | Referent | 96 (28.9) | 85 (23.0) | Referent | 48 (17.0) | 63 (15.1) | Referent | |
| 25.0–29.9 | 279 (31.9) | 304 (31.1) | 1.09 (0.87, 1.37) | 110 | 126 (34.2) | 0.76 (0.51, 1.14) | 102 (36.2) | 151 (36.3) | 1.08 (0.66, 1.75) | |
| ≥30 | 249 (28.4) | 278 (28.4) | 1.03 (0.81, 1.30) | (33.1) | 158 (42.8) | 0.65 (0.44, 0.98) | 132 (46.8) | 202 (48.6) | 1.07 (0.67, 1.71) | |
| Ptrend = 0.78 | 126 (38.0) | Ptrend = 0.04 | Ptrend = 0.82 | |||||||
| Age at menarche, y, No. (%) | 0.80 | |||||||||
| ≤11 | 197 (22.5) | 183 (18.7) | 1.38 (1.05, 1.82) | 93 (28.0) | 81 (22.0) | 1.44 (0.93, 2.21) | 66 (23.4) | 84 (20.2) | 1.04 (0.66, 1.63) | |
| 12–13 | 469 (53.6) | 525 (53.6) | 1.13 (0.90, 1.41) | 148 (44.6) | 175 (47.4) | 1.08 (0.75, 1.56) | 126 (44.7) | 203 (48.8) | 0.81 (0.55, 1.17) | |
| ≥14 | 209 (23.9) | 271 (27.7) | Referent | 91 (27.4) | 113 (30.6) | Referent | 90 (31.9) | 129 (31.0) | Referent | |
| Ptrend = 0.02 | Ptrend = 0.11 | Ptrend = 0.99 | ||||||||
| Age at menopause, y, No. (%) | 0.30 | |||||||||
| ≤50 | 493 (56.3) | 593 (61.1) | Referent | 205 (61.8) | 232 (62.9) | Referent | 176 (62.4) | 294 (70.7) | Referent | |
| >50 | 382 (43.7) | 377 (38.9) | 1.35 (1.11, 1.65) | 129 (38.2) | 137 (37.1) | 1.05 (0.75, 1.46) | 106 (37.6) | 122 (29.3) | 1.60 (1.13, 2.28) | |
| Hormone therapy useb, No. (%) | 0.07 | |||||||||
| Current | 469 (53.6) | 478 (48.8) | 1.04 (0.83, 1.31) | 139 (41.9) | 111 (30.1) | 1.49 (1.03, 2.15) | 104 (36.9) | 96 (23.1) | 1.63 (1.11, 2.41) | |
| Former | 189 (21.6 ) | 270 (27.6) | 0.75 (0.57, 0.98) | 70 (21.1) | 112 (30.4) | 0.72 (0.48, 1.09) | 51 (18.1) | 134 (32.2) | 0.52 (0.35, 0.79) | |
| Never | 217 (24.8) | 231 (23.6) | Referent | 123 (37.0) | 146 (39.5) | Referent | 127 (45.0) | 186 (44.7) | Referent | |
| Ptrend = 0.39 | Ptrend = 0.04 | Ptrend = 0.06 | ||||||||
| Alcohol consumptione, g/day, No. (%) | 0.58 | |||||||||
| None | 413 (47.2) | 510 (52.1) | Referent | 219 (66.0) | 235 (63.7) | Referent | 201 (71.3) | 316 (76.0) | Referent | |
| <10 | 328 (37.5) | 336 (34.3) | 1.19 (0.94, 1.47) | 85 (25.6) | 106 (28.7) | 0.79 (0.55, 1.14) | 66 (23.4) | 79 (19.0) | 1.10 (0.73, 1.65) | |
| ≥10 | 134 (15.3) | 133 (13.6) | 1.26 (0.94, 1.67) | 27 (8.4) | 28 (7.6) | 0.99 (0.56, 1.77) | 15 (5.3) | 21 (5.0) | 0.92 (0.45, 1.90) | |
| Ptrend = 0.06 | Ptrend = 0.49 | Ptrend = 0.89 | ||||||||
OR, odds ratio; CI, confidence interval. Results in bold are statistically significant, results in italics are marginally significant.
a
Adjusted for study site (San Francisco Bay Area Breast Cancer Study versus 4-Corners) and all the listed factors.
b
In referent year.
c
Includes live or still birth
d
Includes both parous and non-parous women.
e
Alcohol consumption was based on lifetime average intake (4-Corners and Mexico subjects), or intake during the reference year (SFBCS).