Table 1.
Breast cancer risk factors among postmenopausal women according to region and self-reported ethnicity.
| Characteristics | US Studies | Mexico Study | ||||
|---|---|---|---|---|---|---|
| Non-Hispanic White | Hispanic | |||||
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| Cases (n = 875) | Controls (n =979) | Cases (n =614) | Controls (n =785) | Cases (n = 426) | Controls (n = 501) | |
| US study site, No. (%) | ||||||
| 4-Corners | 740 (84.6) | 838 (85.6) | 309 (50.3) | 392 (49.9) | N/A | N/A |
| San Francisco Bay Area | 135 (15.4) | 141 (14.4) | 305 (49.7) | 393 (50.1) | ||
| Reference agea,b, y, mean (SD) | 60.7 ( 9.2) | 62.0 ( 9.7) | 59.2 ( 9.1) | 59.2 (9.1) | 57.6 (7.4) | 56.3 (6.9) |
| Family history*,#, No. (%) | ||||||
| Yes | 201 (23.0) | 162 (16.6) | 121 (19.7) | 102 (13.0) | 29 (6.8) | 12 (2.4) |
| No | 674 (77.0) | 817 (83.4) | 493 (80.3) | 683 (87.0) | 397 (93.2) | 489 (97.6) |
| No. of birthsb,c, mean (SD) | 2.4 (1.6) | 2.6 (1.7) | 3.1 (2.1) | 3.7 (2.5) | 3.3 (2.4) | 4.3 (2.7) |
| Age at first birtha,b,c, y, mean (SD) | 23.5 (4.3) | 23.5 (4.5) | 23.0 (5.2) | 22.5 (4.9) | 23.0 (5.7) | 21.4 (4.9) |
| Breast-feedingb,d, No. (%) | ||||||
| Any | 459 (52.5) | 570 (58.2) | 320 (52.1) | 492 (62.7) | 326 (76.5) | 429 (85.6) |
| None | 416 (47.5) | 409 (41.8) | 294 (47.9) | 293 (37.3) | 100 (23.5) | 72 (14.4) |
| Body mass index in referent yeara, kg/m2, mean (SD) | 27.6 (5.8) | 27.5 (6.0) | 29.6(6.1) | 30.2 (6.2) | 30.2(5.9) | 31.0 (5.6) |
| Age at menarche, y, mean (SD) | 12.6 (1.6) | 12.8 (1.6) | 12.6 (1.7) | 12.8 (1.8) | 12.8 (1.7) | 13.0 (1.6) |
| Age at menopauseb, y, mean (SD) | 46.2 (8.2) | 45.2 (8.2) | 45.7 (7.7) | 44.7 (7.6) | 45.7 (6.2) | 45.9 (6.4) |
| Hormone therapy usea,b, No. (%) | ||||||
| Current | 469 (53.6) | 478 (48.8) | 243 (39.6) | 207 (26.4) | 18 (4.2) | 10 (2.0) |
| Former | 189 (21.6) | 270 (27.6) | 121 (19.7) | 246 (31.3) | 84 (19.7) | 64 (12.8) |
| Never | 217 (24.8) | 231 (23.6) | 250 (40.7) | 332 (42.3) | 324 (76.1) | 427 (85.2) |
| Alcohol consumption,b,e, No. (%) | ||||||
| Any | 462 (52.8) | 469 (47.9) | 194 (31.6) | 234 (29.8) | 70 (16.4) | 33 (6.6) |
| None | 413 (47.2) | 510 (52.1) | 420 (68.4) | 551 (70.2) | 356 (83.6) | 468 (93.4) |
| Percent Native American ancestrya,b, mean (SD) | ||||||
| ER statusa | 0.04 (0.06) | 0.04 (0.04) | 0.41 (0.17) | 0.44 (0.18) | 0.66 (0.20) | 0.71 (0.19) |
| ER+ | 493 (82.9) | 348 (76.7) | Not available | |||
| ER− | 102 (18.1) | 106(23.3) | ||||
a
P < 0.05 when comparing NHW controls to US Hispanic controls or NHW cases to US Hispanic cases (ER status only).
b
P < 0.05 when comparing US Hispanic controls to Mexico controls.
c
Among parous (live or still birth) women only (749 cases and 854 controls for NHW; US Hispanic= 559 cases and 737 controls for US Hispanic; 375 cases and 479 controls for Mexico).
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).