Table 1.

Distributions of breast cancer risk factors by race/ethnicity, postmenopausal women residing in California at baseline (n = 48,247), MEC, 1993–2010

All women (n = 48,247)aAfrican American (n = 16,703)aJapanese American (n = 5,063)aLatino (n = 18,752)aWhite (n = 7,729)a
n (%)n (%)n (%)n (%)n (%)
Age at baseline, y
 45–492,992 (6.2)1,339 (8.0)199 (3.9)1,062 (5.7)392 (5.1)
 50–545,972 (12.4)2,152 (12.9)492 (9.7)2,490 (13.3)838 (10.8)
 55–5910,133 (21.0)2,848 (17.1)880 (17.4)4,806 (25.6)1,599 (20.7)
 60–6410,365 (21.5)2,762 (16.5)1,031 (20.4)4,851 (25.9)1,721 (22.3)
 65–699,458 (19.6)3,703 (22.2)1,061 (21.0)3,124 (16.7)1,570 (20.3)
 70–748,038 (16.7)3,350 (20.1)1,151 (22.7)2,142 (11.4)1,395 (18.0)
 75+1,289 (2.7)549 (3.3)249 (4.9)277 (1.5)214 (2.8)
BMI at baseline, kg/m2
 Underweight, <18.5868 (1.8)171 (1.0)354 (7.0)177 (0.9)166 (2.1)
 Normal, 18.5–24.916,612 (34.4)4,047 (24.2)3,437 (67.9)5,662 (30.2)3,466 (44.8)
 Overweight, 25.0–29.917,378 (36.0)6,289 (37.7)1,056 (20.9)7,557 (40.3)2,476 (32.0)
 Obese, ≥30.013,389 (27.8)6,196 (37.1)216 (4.3)5,356 (28.6)1,621 (21.0)
Adult weight gain since age 21,b,c kg
 Quintile 1: −130.5 to <5.48,732 (18.1)1,623 (9.7)2,354 (46.5)2,808 (15.0)1,947 (25.2)
 Quintile 2: 5.4 to <11.38,104 (16.8)1,985 (11.9)1,349 (26.6)3,254 (17.4)1,516 (19.6)
 Quintile 3: 11.3 to <17.69,318 (19.3)3,018 (18.1)775 (15.3)4,008 (21.4)1,517 (19.6)
 Quintile 4: 17.6 to <24.88,678 (18.0)3,522 (21.1)286 (5.6)3,673 (19.6)1,197 (15.5)
 Quintile 5: 25.2 to <90.08,804 (18.2)4,515 (27.0)86 (1.7)3,037 (16.2)1,166 (15.1)
Education
 High school graduate or less26,022 (53.9)7,057 (42.2)1,977 (39.0)13,770 (73.4)3,218 (41.6)
 Some college/technical school13,511 (28.0)5,904 (35.3)1,838 (36.3)3,258 (17.4)2,511 (32.5)
 College graduate4,155 (8.6)1,821 (10.9)761 (15.0)647 (3.5)926 (12.0)
 Graduated and professional school3,855 (8.0)1,713 (10.3)442 (8.7)710 (3.8)990 (12.8)
Smoking status
 Never smoker25,784 (53.4)7,266 (43.5)3,403 (67.2)11,594 (61.8)3,521 (45.6)
 Former smoker14,335 (29.7)5,864 (35.1)1,196 (23.6)4,479 (23.9)2,796 (36.2)
 Current smoker6,858 (14.2)3,334 (20.0)415 (8.2)1,806 (9.6)1,303 (16.9)
Alcohol intake
 Non-drinker29,123 (60.4)10,172 (60.9)3,653 (72.2)11,838 (63.1)3,460 (44.8)
 Drinker17,062 (35.4)5,831 (34.9)1,215 (24.0)6,140 (32.7)3,876 (50.1)
Moderate or vigorous physical activity,c h/d
 03,840 (8.0)972 (5.8)119 (2.4)2,436 (13.0)313 (4.0)
 Quartile 1: <0.47,953 (16.5)2,871 (17.2)707 (14.0)3,507 (18.7)868 (11.2)
 Quartile 2: 0.4 to <0.711,901 (24.7)4,845 (29.0)1,335 (26.4)4,044 (21.6)1,677 (21.7)
 Quartile 3: 0.7 to <1.210,589 (21.9)3,721 (22.3)1,246 (24.6)3,730 (19.9)1,892 (24.5)
 Quartile 4: 1.2 to <13.312,153 (25.2)3,591 (21.5)1,575 (31.1)4,143 (22.1)2,844 (36.8)
Energy,c kcal/d
 Quintile 1: 417.4 to <1,152.89,237 (19.1)3,933 (23.5)905 (17.9)2,999 (16.0)1,400 (18.1)
 Quintile 2: 1,152.8 to <1,533.29,237 (19.1)3,186 (19.1)1,227 (24.2)3,044 (16.2)1,780 (23.0)
 Quintile 3: 1,533.2 to <1,947.09,237 (19.1)3,036 (18.2)1,224 (24.2)3,299 (17.6)1,678 (21.7)
 Quintile 4: 1,947.0 to <2,606.99,237 (19.1)2,959 (17.7)1,003 (19.8)3,745 (20.0)1,530 (19.8)
 Quintile 5: 2,606.9 to <7,211.39,237 (19.1)2,889 (17.3)509 (10.1)4,891 (26.1)948 (12.3)
Ever had mammogram
 Yes5,192 (10.8)1,293 (7.7)578 (11.4)2,596 (13.8)725 (9.4)
 No41,384 (85.8)14,784 (88.5)4,356 (86.0)15,371 (82.0)6,873 (88.9)
Family history of breast cancerd
 Yes4,975 (10.3)1,003 (13.0)1,832 (11.0)516 (10.2)1,624 (8.7)
 No39,380 (81.6)6,269 (81.1)13,498 (80.8)4,286 (84.7)15,327 (81.7)
Age at first birth, y
 Nulliparous5,691 (11.8)2,261 (13.5)800 (15.8)1,528 (8.1)1,102 (14.3)
 <2017,466 (36.2)7,442 (44.6)354 (7.0)7,468 (39.8)2,202 (28.5)
 21–3021,009 (43.5)5,706 (34.2)3,288 (64.9)8,262 (44.1)3,753 (48.6)
 >302,665 (5.5)668 (4.0)516 (10.2)960 (5.1)521 (6.7)
Age at menarche, y
 <1222,666 (47.0)7,988 (47.8)2,251 (44.5)8,625 (46.0)3,802 (49.2)
 13–1418,382 (38.1)6,211 (37.2)2,029 (40.1)7,147 (38.1)2,995 (38.8)
 >146,344 (13.1)2,139 (12.8)713 (14.1)2,646 (14.1)846 (10.9)
Parity
 Nulliparous5,691 (11.8)2,261 (13.5)800 (15.8)1,528 (8.1)1,102 (14.3)
 15,432 (11.3)2,651 (15.9)581 (11.5)1,271 (6.8)929 (12.0)
 2–318,106 (37.5)5,825 (34.9)2,784 (55.0)5,811 (31.0)3,686 (47.7)
 ≥418,342 (38.0)5,735 (34.3)868 (17.1)9,805 (52.3)1,934 (25.0)
Menopause status
 Natural menopause26,584 (55.1)7,611 (45.6)3,354 (66.2)11,121 (59.3)4,498 (58.2)
 Oophorectomy7,685 (15.9)3,198 (19.1)718 (14.2)2,395 (12.8)1,374 (17.8)
 Hysterectomy9,441 (19.6)4,153 (24.9)552 (10.9)3,402 (18.1)1,334 (17.3)
Hormone replacement therapy
 Never estrogen use23,367 (48.4)8,752 (52.4)2,385 (47.1)9,303 (49.6)2,927 (37.9)
 Past estrogen use9,519 (19.7)3,672 (22.0)737 (14.6)3,562 (19.0)1,548 (20.0)
 Current unopposed estrogen use6,312 (13.1)2,037 (12.2)768 (15.2)2,177 (11.6)1,330 (17.2)
 Current estrogen–progesterone use6,083 (12.6)1,231 (7.4)1,008 (19.9)2,183 (11.6)1,661 (21.5)
  • aNs may not add to racial/ethnic totals and percentages may not add to 100 due to missing.

  • bDifference between baseline weight and weight at age 21.

  • cQuintiles or quartiles based on study population distribution.

  • dAt least one of mother of sisters had breast cancer.