Table 1.
Clinicopathologic Characteristics and Endocrine Resistance status of patients in training, internal and external validation cohorts.
| Characteristics | Training cohort N = 433 (%) |
Internal validation cohort N = 160 (%) |
External validation cohort N = 151 (%) |
Total N = 744 (%) |
P value |
|---|---|---|---|---|---|
| age | <0.001 | ||||
| ≤35 | 27(6.2) | 29(18.1) | 8(5.3) | 64(8.6) | |
| 35–50 | 203(47.0) | 80(50.0) | 76(50.3) | 359(48.3) | |
| ≥50 | 202(46.8) | 51(31.9) | 67(44.4) | 320(43.1) | |
| ER∗ | 0.842 | ||||
| Low | 85(19.6) | 28(17.5) | 29(19.2) | 142(19.1) | |
| High | 348(80.4) | 132(82.5) | 122(80.8) | 602(80.9) | |
| PR+ | <0.001 | ||||
| Low | 188(43.4) | 95(59.4) | 51(33.8) | 334(44.9) | |
| High | 245(56.6) | 65(40.6) | 100(66.2) | 410(55.1) | |
| HER2∗∗ | 0.067 | ||||
| Negative | 311(71.8) | 99(61.9) | 104(68.9) | 514(69.1) | |
| Positive | 122(28.2) | 61(38.1) | 47(31.1) | 230(30.9) | |
| Ki-67++ | <0.001 | ||||
| Negative | 72(16.6) | 71(44.4) | 53(36.6) | 196(26.6) | |
| Positive | 361(83.4) | 89(55.6) | 92(63.4) | 542(73.4) | |
| Stage | <0.001 | ||||
| I | 84(19.4) | 5(3.1) | 37(24.5) | 126(16.9) | |
| II | 287(66.3) | 109(68.1) | 76(50.3) | 472(63.4) | |
| III | 62(14.3) | 46(28.8) | 38(25.2) | 146(19.6) | |
| T stage | <0.001 | ||||
| T1 | 95(21.9) | 5(3.1) | 59(39.1) | 159(21.4) | |
| T2 | 264(61.0) | 84(52.5) | 83(55.0) | 431(57.9) | |
| T3-4 | 74(17.1) | 71(44.4) | 9(6.0) | 154(20.7) | |
| N stage | <0.001 | ||||
| N0 | 262(60.5) | 58(36.3) | 77(51.0) | 397(53.4) | |
| N1 | 124(28.6) | 63(39.4) | 38(25.2) | 225(30.2) | |
| N2-3 | 47(10.9) | 39(24.4) | 36(23.8) | 122(16.4) | |
| Grade | 0.166 | ||||
| I-II | 249(57.5) | 101(66.0) | 93(61.6) | 443(60.1) | |
| III | 184(42.5) | 52(34.0) | 58(38.4) | 294(39.9) | |
| Pathologic type | 0.016 | ||||
| IDC | 406(93.8) | 156(97.5) | 151(100.0) | 713(95.8) | |
| ILC | 17(3.9) | 0(0.0) | 0(0.0) | 17(2.3) | |
| Other | 10(2.3) | 4(2.5) | 0(0.0) | 14(1.9) | |
| Surgery | <0.001 | ||||
| Mastectomy | 194(44.8) | 96(60.0) | 118(78.1) | 408(54.8) | |
| BCS | 239(55.2) | 64(40.0) | 33(21.9) | 336(35.2) | |
| Chemotherapy | <0.001 | ||||
| No | 82(18.9) | 0(0) | 17(11.3) | 99(13.3) | |
| Yes | 351(81.1) | 160(100) | 134(88.7) | 645(86.7) | |
| Chemotherapy treatment | <0.001 | ||||
| Anthracycline and paclitaxel-based | 246(70.1) | 160(100) | 100(74.6) | 506(78.4) | |
| Paclitaxel-based | 79(22.5) | 0(0) | 21(15.7) | 100(15.5) | |
| Anthracycline-based | 26(7.4) | 0(0) | 13(9.7) | 39(6.0) | |
| Endocrine therapy | <0.001 | ||||
| Aromatase inhibitor | 197(45.5) | 79(59.8) | 27(17.9) | 303(42.3) | |
| Tamoxifen | 236(54.5) | 53(40.2) | 124(82.1) | 413(57.7) | |
| Endocrine Resistance | 0.391 | ||||
| No | 414(95.6) | 149(93.1) | 145(96.0) | 708(95.2) | |
| Yes | 19(4.4) | 11(6.9) | 6(4.0) | 36(4.8) |
Abbreviations: ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor2; IDC, Invasive ductal carcinoma; ILC, Invasive lobular carcinoma; BCS, breast conserving surgery.
∗Cases where ≥10% of tumor cells stained positive for ER with immunohistochemistry (IHC) were considered high.
+Cases where ≥20% of tumor cells stained positive for PR with IHC were considered high.
∗∗Cases that showed either 3+ IHC staining or had gene copy number＞2.0 were considered HER2 positive.
++Cases where ≥14% of tumor cells stained positive for Ki-67 with IHC were considered positive.
P values of the comparison between 3 cohorts were generated by χ2 test for categorical variables.