Table 1 Characteristics of breast cancer patients in the WECARE I and II Study
Characteristics | CBC cases | UBC controls |
|---|---|---|
N (%) | N (%) | |
Overall numbers | 1521 (100) | 2212 (100) |
Study area | ||
Iowaa | 201(13) | 314 (14) |
Seattleb | 224 (15) | 317 (14) |
Ontarioc | 159 (10) | 157 (7) |
Californiad | 658 (43) | 967 (44) |
Denmarke | 279 (18) | 457 (21) |
Age at first breast cancer (years) | ||
≤39 | 268 (18) | 384 (17) |
40–49 | 808 (53) | 1180 (53) |
50–54 | 445 (29) | 648 (29) |
Age at CBC/reference date (years) | ||
≤39 | 100 (6) | 147 (7) |
40–49 | 446 (29) | 691 (31) |
50–59 | 719 (48) | 1087 (49) |
≥60 | 256 (17) | 287 (13) |
Year of diagnosis of first breast cancer | ||
1985–1989 | 303 (20) | 580 (26) |
1990–1994 | 572 (38) | 871 (39) |
1995–1999 | 426 (28) | 551 (25) |
2000–2004 | 186 (12) | 190 (9) |
2005–2008 | 34 (2) | 20 (1) |
Time since first breast cancer (years) | ||
1–4 | 586 (39) | 986 (45) |
5–9 | 574 (38) | 804 (36) |
≥10 | 361 (24) | 422 (19) |
First-degree family history of breast cancer | ||
Yes | 497 (33) | 466 (21) |
No | 1004 (66) | 1706 (77) |
Unknown | 20 (1) | 40 (2) |
Lobular histology of first breast cancer | ||
Yes | 179 (12) | 223 (10) |
No | 1342 (88) | 1989 (90) |
Stage of first breast cancer | ||
Local | 1061 (70) | 1442 (65) |
Regional | 448 (29) | 759 (34) |
Unknown | 12 (1) | 11 (1) |
ER/PR status of the first breast cancer | ||
Positive | 863 (57) | 1379 (62) |
Negative | 413 (27) | 473 (21) |
Unknown | 245 (16) | 360 (16) |
Radiation for first breast cancerf | ||
Yes | 880 (58) | 1686 (76) |
No | 641 (42) | 525 (24) |
Chemotherapy for first breast cancer | ||
Yes | 822 (54) | 1289 (58) |
No | 699 (46) | 923 (42) |
Tamoxifen use for first breast cancer | ||
Yes | 467 (31) | 787 (36) |
No | 1054 (69) | 1425 (64) |
Other endocrine therapy for first breast cancerg | ||
Yes | 89 (6) | 141 (6) |
No | 1432 (94) | 2071 (94) |