Table 2.
Breast cancer characteristics by estrogen plus progestin use at baseline*
| Estrogen plus progestin | No hormone therapy | ||
|---|---|---|---|
| Characteristic | No. (%) (n = 1097) | No. (%) (n = 1139) | P † |
| Tumor size | .83 | ||
| ≤0.5 cm | 137 (12.9) | 130 (11.9) | |
| >0.5–1 cm | 290 (27.4) | 302 (27.7) | |
| >1–2 cm | 428 (40.5) | 437 (40.1) | |
| >2 cm | 203 (19.2) | 222 (20.3) | |
| No. of positive lymph nodes | .25 | ||
| None | 745 (75.3) | 778 (78.4) | |
| 1–3 | 173 (17.5) | 155 (15.6) | |
| >3 | 71 (7.2) | 59 (5.9) | |
| Positive lymph nodes | 245 (24.7) | 218 (21.9) | .13 |
| Summary stage (SEER) | .04 | ||
| Localized | 827 (76.0) | 869 (77.1) | |
| Regional | 250 (23.0) | 229 (20.3) | |
| Distant | 5 (0.5) | 15 (1.3) | |
| Unknown | 6 (0.6) | 14 (1.2) | |
| SEER stage (regional/distant) | 255 (23.6) | 244 (21.9) | .36 |
| Histology | .07 | ||
| Ductal | 668 (61.4) | 717 (63.6) | |
| Lobular | 121 (11.1) | 124 (11.0) | |
| Ductal and lobular | 177 (16.3) | 158 (14.0) | |
| Tubular | 55 (5.1) | 35 (3.1) | |
| Other | 67 (6.2) | 93 (8.3) | |
| Grade | .008 | ||
| Unknown | 85 (7.8) | 112 (9.9) | |
| Well differentiated | 317 (29.1) | 279 (24.8) | |
| Moderately differentiated | 470 (43.2) | 460 (40.8) | |
| Poorly differentiated/anaplastic | 216 (19.9) | 276 (24.5) | |
| Estrogen receptor assay | <.001 | ||
| Positive | 923 (84.1) | 867 (76.1) | |
| Negative | 104 (9.5) | 175 (15.4) | |
| Borderline | 3 (0.3) | 0 (0.0) | |
| Unknown/not done/missing | 67 (6.1) | 97 (8.5) | |
| Progesterone receptor assay | <.001 | ||
| Positive | 795 (72.5) | 720 (63.2) | |
| Negative | 215 (19.6) | 299 (26.3) | |
| Borderline | 5 (0.5) | 3 (0.3) | |
| Unknown/not done/missing | 82 (7.5) | 117 (10.3) | |
| Erb2 (HER2) status | .74 | ||
| Positive | 118 (10.8) | 122 (10.7) | |
| Negative | 612 (55.8) | 663 (58.2) | |
| Borderline | 9 (0.8) | 8 (0.7) | |
| Unknown/not done/missing | 358 (32.6) | 346 (30.4) | |
| Triple-negative tumor status | <.001 | ||
| Triple negative (ER−/PR−/HER2−) | 42 (3.8) | 92 (8.1) | |
| Other (includes borderline) | 689 (62.8) | 690 (60.6) | |
| Unknown/missing ER/PR/HER2 all/some | 366 (33.4) | 357 (31.3) |
* Some categories do not add up to the total number of cases due to missing data. ER = estrogen receptor; Erb2 and HER2 = human epidermal growth factor receptor 2; PR = progesterone receptor; SEER = Surveillance Epidemiolgy and End Results.
† Based on χ2 test of association where brackets indicate which rows were included in tests. All statistical tests were two-sided.