Table 1. comparison of baseline characteristics between patients with pure IDC and IDC-DCIS.
| Characteristics | Whole cohort | Pure IDC | IDC-DCIS | P | Matched cohort | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | No. | % | ||||
| Age | <0.001 | ||||||||||
| <60 | 127,300 | 51.4 | 47,423 | 48.3 | 79,877 | 53.4 | 33,271 | 46.4 | |||
| ≥60 | 120,274 | 48.6 | 50,674 | 51.7 | 69,600 | 46.6 | 38,391 | 53.6 | |||
| Race | <0.001 | ||||||||||
| White | 194,798 | 78.7 | 78,216 | 79.7 | 116,582 | 78.0 | 61,281 | 85.5 | |||
| Black | 27,967 | 11.3 | 11,911 | 12.1 | 16,056 | 10.7 | 5,843 | 8.2 | |||
| Asian or Indian | 23,370 | 9.4 | 7,442 | 7.6 | 15,928 | 10.7 | 4,428 | 6.2 | |||
| Unknown | 1,439 | 0.6 | 528 | 0.5 | 911 | 0.6 | 110 | 0.2 | |||
| Histologic grade | <0.001 | ||||||||||
| I | 50,456 | 20.4 | 19,862 | 20.2 | 30,594 | 20.5 | 17,051 | 23.8 | |||
| II | 99,455 | 40.2 | 34,463 | 35.1 | 64,992 | 43.5 | 28,352 | 39.6 | |||
| III | 92,590 | 37.4 | 41,438 | 42.2 | 51,152 | 34.2 | 25,598 | 35.7 | |||
| Unknown | 5,073 | 2.0 | 2,334 | 2.4 | 2,739 | 1.8 | 661 | 0.9 | |||
| AJCC stage | <0.001 | ||||||||||
| I | 133,239 | 53.8 | 47,863 | 48.8 | 85,376 | 57.1 | 41,932 | 58.5 | |||
| IIA | 60,170 | 24.3 | 25,467 | 26.0 | 34,703 | 23.2 | 18,079 | 25.2 | |||
| IIB | 27,593 | 11.1 | 12,071 | 12.3 | 15,522 | 10.4 | 7,009 | 9.8 | |||
| IIIA | 16,057 | 6.5 | 6,897 | 7.0 | 9,160 | 6.1 | 3,222 | 4.5 | |||
| IIIB | 4,197 | 1.7 | 2,902 | 3.0 | 1,295 | 0.9 | 492 | 0.7 | |||
| IIIC | 6,318 | 2.6 | 2,897 | 3.0 | 3,421 | 2.3 | 928 | 1.3 | |||
| T stage | <0.001 | ||||||||||
| T1 | 159,803 | 64.5 | 57,103 | 58.2 | 102,700 | 68.7 | 49,444 | 69.0 | |||
| T2 | 72,846 | 29.4 | 32,334 | 33.0 | 40,512 | 27.1 | 19,685 | 27.5 | |||
| T3 | 9,814 | 4.0 | 5,198 | 5.3 | 4,616 | 3.1 | 1,936 | 2.7 | |||
| T4a–c | 3,810 | 1.5 | 2,571 | 2.6 | 1,239 | 0.8 | 454 | 0.6 | |||
| T4d | 1,301 | 0.5 | 891 | 0.9 | 410 | 0.3 | 143 | 0.2 | |||
| N stage | <0.001 | ||||||||||
| N0 | 171,621 | 69.3 | 67,133 | 68.4 | 104,488 | 69.9 | 53,811 | 75.1 | |||
| N1 | 56,025 | 22.6 | 22,355 | 22.8 | 33,670 | 22.5 | 14,380 | 20.1 | |||
| N2 | 13,610 | 5.5 | 5,712 | 5.8 | 7,898 | 5.3 | 2,543 | 3.5 | |||
| N3 | 6,318 | 2.6 | 2,897 | 3.0 | 3,421 | 2.3 | 928 | 1.3 | |||
| Surgery | <0.001 | ||||||||||
| BCS | 151,200 | 61.1 | 61,219 | 62.4 | 89,981 | 60.2 | 48,559 | 67.8 | |||
| Mastectomy | 96,374 | 38.9 | 36,878 | 37.6 | 59,496 | 39.8 | 23,103 | 32.2 | |||
| Radiation | <0.001 | ||||||||||
| No or unknown | 110,685 | 44.7 | 42,881 | 43.7 | 67,804 | 45.4 | 29,233 | 40.8 | |||
| Yes | 136,889 | 55.3 | 55,216 | 56.3 | 81,673 | 54.6 | 42,429 | 59.2 | |||
| Chemotherapy | <0.001 | ||||||||||
| No or unknown | 138,286 | 55.9 | 52,523 | 53.5 | 85,763 | 57.4 | 42,715 | 59.6 | |||
| Yes | 109,288 | 44.1 | 45,574 | 46.5 | 63,714 | 42.6 | 28,947 | 40.4 | |||
| ER | <0.001 | ||||||||||
| Negative | 50,673 | 20.5 | 25,618 | 26.1 | 25,055 | 16.8 | 14,058 | 19.6 | |||
| Positive | 190,683 | 77.0 | 69,160 | 70.5 | 121,523 | 81.3 | 56,481 | 78.8 | |||
| Unknown | 6,218 | 2.5 | 3,319 | 3.4 | 2,899 | 1.9 | 1,123 | 1.6 | |||
| PR | <0.001 | ||||||||||
| Negative | 74,620 | 30.1 | 35,015 | 35.7 | 39,605 | 26.5 | 20,139 | 28.1 | |||
| Positive | 165,190 | 66.7 | 59,176 | 60.3 | 106,014 | 70.9 | 50,214 | 70.1 | |||
| Unknown | 7,764 | 3.1 | 3,906 | 4.0 | 3,858 | 2.6 | 1,309 | 1.8 | |||
| HER2 (since 2010) | <0.001 | ||||||||||
| Negative | 113,492 | 80.4 | 42,575 | 82.0 | 70,917 | 79.5 | 33,932 | 87.5 | |||
| Positive | 21,238 | 15.0 | 6,717 | 12.9 | 14,521 | 16.3 | 3,866 | 10.0 | |||
| Unknown | 6,431 | 4.6 | 2,647 | 5.1 | 3,784 | 4.2 | 981 | 2.5 | |||
IDC, invasive ductal breast cancer; DCIS, ductal carcinoma in situ; BCS, breast conserving surgery.