TABLE 1.
Description of Study Sample: Postmenopausal Women With an Intact Uterus (Age: 50–79 Years) Enrolled in the Women’s Health Initiative Randomized Trial of Estrogen Plus Progesterone Replacement Therapy (1993–1998)
| First-degree Family History |
|||||
|---|---|---|---|---|---|
| Yes |
No |
||||
| Variable | Full Sample (n = 16,608) |
EP (n = 1009) |
Placebo (n = 895) |
EP (n = 7497) |
Placebo (n = 7207) |
| Invasive breast cancers; no. | 349 | 35 | 25 | 164 | 125 |
| Woman-years; no. | 92,292 | 5596 | 4900 | 41,998 | 39,798 |
| No. (%) | No. (%) | No. (%) | No. (%) | No. (%) | |
|
|
|||||
| Age (years) | |||||
| 50–59 | 5522 (33) | 281 (28) | 264 (30) | 2558 (34) | 2419 (34) |
| 60–69 | 7510 (45) | 464 (46) | 399 (45) | 3389 (45) | 3258 (45) |
| 70–79 | 3576 (22) | 264 (26) | 232 (26) | 1550 (21) | 1530 (21) |
| Ethnicity | |||||
| Hispanic | 888 (5) | 40 (4) | 32 (4) | 432 (6) | 384 (5) |
| Black | 1124 (7) | 45 (5) | 51 (6) | 504 (7) | 524 (7) |
| White, non-Hispanic | 13,945 (84) | 886 (88) | 784 (88) | 6254 (84) | 6021 (84) |
| Other | 610 (4) | 36 (4) | 23 (3) | 291 (4) | 260 (4) |
| Educational attainment | |||||
| <High school graduate | 1114 (7) | 67 (7) | 43 (5) | 508 (7) | 496 (7) |
| High school graduate | 3222 (20) | 194 (19) | 188 (21) | 1420 (19) | 1420 (20) |
| Some college | 6415 (39) | 384 (38) | 348 (39) | 2972 (40) | 2711 (38) |
| Collage graduate | 5753 (35) | 359 (36) | 308 (35) | 2556 (35) | 2530 (35) |
| Household income <$35,000 | 7521 (47) | 508 (52) | 453 (52) | 3827 (53) | 3768 (54) |
| BMI (m/kg2) | |||||
| Underweight (<18.5) | 57 (<1) | 5 (<1) | 4 (<1) | 17 (<1) | 31 (<1) |
| Normal (18.5–24.9) | 5004 (30) | 295 (29) | 277 (31) | 2263 (30) | 2169 (30) |
| Overweight (25–29.9) | 5831 (35) | 346 (34) | 317 (35) | 2649 (35) | 2519 (35) |
| Obese (≥30) | 5643 (34) | 362 (36) | 296 (33) | 2539 (34) | 2446 (34) |
| Diet | |||||
| Fruit ≥1.5 servings/day | 8453 (51) | 527 (52) | 466 (52) | 3777 (51) | 3683 (51) |
| Vegetables ≥2 servings/day | 7469 (45) | 491 (49) | 420 (47) | 3294 (44) | 3264 (45) |
| Walking ≥10 minutes episode (days/week) | |||||
| <1 | 7498 (45) | 433 (43) | 417 (47) | 3386 (45) | 3262 (45) |
| 1–2 | 4185 (25) | 265 (26) | 229 (26) | 1890 (25) | 1801 (25) |
| ≥3 | 4852 (29) | 308 (31) | 247 (28) | 2188 (29) | 2109 (29) |
| Smoking status | |||||
| Current | 1718 (10) | 95 (9) | 87 (10) | 785 (11) | 751 (11) |
| Former | 6519 (40) | 388 (39) | 357 (40) | 2974 (40) | 2800 (39) |
| Never | 8177 (50) | 519 (52) | 439 (50) | 3659 (49) | 3560 (50) |
| Alcohol (drinks/week) | |||||
| <1 | 4717 (29) | 304 (30) | 242 (27) | 2095 (28) | 2076 (29) |
| 1–6 | 9657 (59) | 577 (58) | 534 (60) | 4417 (59) | 4129 (58) |
| ≥7 | 2095 (13) | 120 (12) | 114 (13) | 927 (12) | 934 (13) |
| Previous breast biopsies | |||||
| 0 | 12,618 (83) | 708 (78) | 668 (80) | 5632 (84) | 5610 (84) |
| 1 | 1928 (13) | 157 (17) | 128 (15) | 799 (12) | 844 (13) |
| ≥2 | 578 (4) | 39 (4) | 44 (5) | 251 (4) | 244 (4) |
| Age at menarche <12 years | 7631 (46) | 495 (49) | 387 (43) | 3371 (45) | 3378 (47) |
| Number of term pregnancies | |||||
| 0 | 1688 (10) | 95 (9) | 90 (10) | 761 (10) | 742 (10) |
| 1–2 | 8939 (54) | 522 (52) | 455 (51) | 4096 (55) | 3866 (54) |
| ≥3 | 5903 (36) | 390 (39) | 348 (39) | 2601 (35) | 2564 (36) |
| Age at first birth ≥30 (among parous women) | 1344 (10) | 85 (10) | 62 (9) | 638 (11) | 559 (10) |
| Breast-fed >6 months (among parous women) | 4669 (32) | 272 (30) | 261 (33) | 2141 (32) | 1995 (31) |
| EP use prior to enrollment | 4310 (26) | 266 (26) | 249 (28) | 1963 (26) | 1832 (25) |
EP indicates estrogen plus progesterone replacement therapy.