Skip to main content
. Author manuscript; available in PMC: 2018 May 1.
Published in final edited form as: Cancer Epidemiol Biomarkers Prev. 2016 Dec 8;26(5):692–701. doi: 10.1158/1055-9965.EPI-16-0721

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



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).