Table 2.
Distribution of pathologic features by age group.
| Total N = 1147, N (%) | ≤30 years, N = 146, N (%) | 31–35 years, N = 318, N (%) | 36–40 years, N = 683, N (%) | P | |
|---|---|---|---|---|---|
| Subtype | 0.48 | ||||
| Luminal A-like | 376 (32.9) | 48 (33.1) | 98 (30.9) | 230 (33.8) | |
| Luminal B-like | 485 (42.4) | 61 (42.1) | 140 (44.2) | 284 (41.7) | |
| ER and/or PR + , HER2−, grade 3 | 250 (21.9) | 29 (20.0) | 70 (22.1) | 151 (22.2) | |
| ER and/or PR + , HER2 + | 235 (20.6) | 32 (22.1) | 70 (22.1) | 133 (19.5) | |
| HER2-enriched | 95 (8.3) | 12 (8.3) | 35 (11.0) | 48 (7.1) | |
| Triple-negative | 187 (16.4) | 24 (16.6) | 44 (13.9) | 119 (17.5) | |
| Missing | 4 | ||||
| Stage | 0.11 | ||||
| I | 402 (35.1) | 44 (30.1) | 104 (32.7) | 254 (37.2) | |
| II | 502 (43.8) | 70 (48.0) | 133 (41.8) | 299 (43.8) | |
| III | 186 (16.2) | 21 (14.4) | 65 (20.4) | 100 (14.6) | |
| IV | 57 (5.0) | 11 (7.5) | 16 (5.0) | 30 (4.4) | |
| Histologic subtype | |||||
| Ductal | 798 (69.6%) | 107 (73.3%) | 239 (75.2%) | 452 (66.2%) | 0.11 |
| Lobular | 48 (4.2%) | 5 (3.4%) | 9 (2.8%) | 34 (5.0%) | |
| Ductal and lobular features | 114 (9.9%) | 13 (8.9%) | 26 (8.2%) | 75 (11.0%) | |
| Other | 141 (12.3%) | 17 (11.6%) | 37 (11.6%) | 87 (12.7%) | |
| Unknown | 46 (4.0%) | 4 (2.7%) | 7 (2.2%) | 35 (5.1%) | |
| ER | 0.93 | ||||
| Positive | 836 (72.9) | 108 (74.0) | 230 (72.3) | 498 (72.9) | |
| Negative | 311 (27.1) | 38 (26.0) | 88 (27.7) | 185 (27.1) | |
| PR | 0.36 | ||||
| Positive | 759 (66.2) | 92 (63.0) | 204 (64.2) | 463 (67.8) | |
| Negative | 388 (33.8) | 54 (37.0) | 114 (35.9) | 220 (32.2) | |
| HER2 | 0.28 | ||||
| Positive | 330 (28.8) | 44 (30.1) | 105 (33.0) | 181 (26.5) | |
| Negative | 814 (71.0) | 102 (69.9) | 212 (66.7) | 500 (73.2) | |
| Missing | 3 | ||||
| Grade | 0.46 | ||||
| I/II | 488 (42.7) | 60 (41.4) | 127 (40.2) | 301 (44.2) | |
| III | 654 (57.3) | 85 (58.6) | 189 (59.8) | 380 (55.8) | |
| Missing | 5 | ||||
| Tumour necrosis | 0.73 | ||||
| Yes | 178 (15.9) | 23 (16.1) | 53 (16.8) | 102 (15.5) | |
| No | 879 (78.6) | 115 (80.4) | 247 (78.4) | 517 (78.3) | |
| No answer/NA/missing | 90 | ||||
| Lymphocytic infiltration | 0.93 | ||||
| None/Mild | 781 (69.9) | 105 (73.4) | 221 (70.2) | 455 (68.9) | |
| Moderate or marked | 309 (27.6) | 37 (25.9) | 85 (27.0) | 187 (28.3) | |
| No answer/NA/missing | 57 | ||||
| Fibrotic focus | 0.27 | ||||
| Yes | 136 (12.2) | 15 (10.5) | 41 (13.0) | 80 (12.1) | |
| No | 690 (61.7) | 86 (60.1) | 184 (58.4) | 420 (63.6) | |
| No answer/NA/missing | 321 | ||||
| Margins | 0.05 | ||||
| Pushing/circumscribed | 245 (21.9) | 40 (28.0) | 75 (23.8) | 130 (19.7) | |
| Invasive | 642 (57.4) | 73 (51.1) | 166 (52.7) | 403 (61.1) | |
| No answer/NA/missing | 260 | ||||
| Genetic testing | 0.008 | ||||
| BRCA1 positive | 84 (7.3%) | 15 (10.3%) | 28 (8.8%) | 41(6.0%) | |
| BRCA2 positive | 47 (4.1%) | 6 (4.1%) | 9 (2.8%) | 32 (4.7%) | |
| BRCA1/2 not detected/VUS | 972 (84.7%) | 123 (84.3%) | 276 (86.8%) | 573 (83.9%) | |
| Not tested | 44 (3.9%) | 2 (1.4%) | 5 (1.6%) | 37 (5.4%) |