Table 1.
Patient and tumor characteristics at primary breast cancer diagnosis by intratumor heterogeneity of ER
| STO-3 trial |
||||
|---|---|---|---|---|
| Low heterogeneity | High heterogeneity | P* | Total No. of patients | |
| No. (%) | No. (%) | |||
| STO-3 trial arm | .93 | |||
| Tamoxifen-treated arm | 205 (51.6) | 102 (52.0) | 307 | |
| Untreated arm | 192 (48.4) | 94 (48.0) | 286 | |
| Patient characteristics | ||||
| Calendar period of primary diagnosis | .80 | |||
| 1976–1979 | 59 (14.9) | 33 (16.8) | 92 | |
| 1980–1984 | 146 (36.8) | 69 (35.2) | 215 | |
| 1985–1990 | 192 (48.3) | 94 (48.0) | 286 | |
| Age at primary diagnosis, y | .71 | |||
| 45–54 | 43 (10.8) | 17 (8.7) | 60 | |
| 55–64 | 199 (50.1) | 98 (50.0) | 297 | |
| 65–74 | 155 (39.1) | 81 (41.3) | 236 | |
| Primary tumor characteristics | ||||
| Type of surgery | .53 | |||
| Breast-conserving surgery and RT | 93 (23.4) | 41 (20.9) | 134 | |
| Mastectomy | 304 (76.6) | 155 (79.1) | 459 | |
| Progesterone receptor status | .92 | |||
| Positive | 266 (68.4) | 131 (67.9) | 397 | |
| Negative | 123 (31.6) | 62 (32.1) | 185 | |
| Unknown | 8 | 3 | 11 | |
| HER2 status† | 1.00 | |||
| Positive | 17 (4.3) | 8 (4.1) | 25 | |
| Negative | 378 (95.7) | 187 (95.9) | 565 | |
| Unknown | 2 | 1 | 3 | |
| Ki-67 status‡ | .06 | |||
| Positive | 90 (23.8) | 30 (16.6) | 120 | |
| Negative | 288 (76.2) | 151 (83.4) | 439 | |
| Unknown | 19 | 15 | 34 | |
| Tumor grade | .52 | |||
| 1 | 86 (21.9) | 44 (22.9) | 130 | |
| 2 | 248 (63.1) | 126 (65.6) | 374 | |
| 3 | 59 (15.0) | 22 (11.5) | 81 | |
| Unknown | 4 | 4 | 8 | |
| Tumor size, mm | .36 | |||
| pT < 20 | 319 (81.2) | 164 (84.5) | 483 | |
| pT ≥ 20 | 74 (18.8) | 30 (15.5) | 104 | |
| Unknown | 4 | 2 | 6 | |
| Intrinsic subtypes (PAM50) | .21 | |||
| Basal | 6 (1.6) | 1 (0.6) | 7 | |
| HER2-enriched | 17 (4.7) | 4 (2.3) | 21 | |
| Luminal A | 233 (64.0) | 103 (59.2) | 336 | |
| Luminal B | 80 (22.0) | 46 (26.4) | 126 | |
| Normal-like | 28 (7.7) | 20 (11.5) | 48 | |
| Unknown | 33 | 22 | 55 | |
*
Two-sided Fisher exact test. ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; RT = radiotherapy; STO-3 = Stockholm Tamoxifen trial 3.
†
HER2 positive defined as 3+ by immunohistochemistry.
‡
Ki-67 cutoff for positivity at 15%.