Comparison of treatments and clinical and pathological characteristics of tumours according to age at breast cancer diagnosis
| Total | <41 years | 41–69 years | ≥70 years | P value | |
| Number of patients | 594 | 37 (6.2%) | 472 (79.5%) | 85 (14.3%) | |
| Tumour size | 0.1 (T1 vs T2–4) | ||||
| T1 | 384 (64.6%) | 20 (54.1%) | 315 (66.7%) | 49 (57.6%) | |
| T2 | 189 (31.8%) | 14 (37.8%) | 144 (30.5%) | 31 (36.5%) | |
| T3 | 19 (3.2%) | 3 (8.1%) | 12 (2.5%) | 4 (4.7%) | |
| T4 | 2 (0.3%) | 0 (0%) | 1 (0.2%) | 1 (1.2%) | |
| Nodal status | 0.5 (N0 vs N1–3) | ||||
| N0 | 368 (62.0%) | 21 (56.8%) | 298 (63.1%) | 49 (57.6%) | |
| N1 | 162 (27.3%) | 10 (27.0%) | 125 (26.5%) | 27 (31.8%) | |
| N2 | 50 (8.4%) | 4 (10.8%) | 40 (8.5%) | 6 (7.1%) | |
| N3 | 14 (2.4%) | 2 (5.4%) | 9 (1.9%) | 3 (3.5%) | |
| Histopathology | 0.040 | ||||
| Ductal | 456 (76.8%) | 30 (81.1%) | 368 (78.0%) | 58 (68.2%) | |
| Lobular | 91 (15.3%) | 3 (8.1%) | 74 (15.7%) | 14 (16.5%) | |
| Other | 47 (7.9%) | 4 (10.8%) | 30 (6.4%) | 13 (15.3%) | |
| Multifocal cancer | 0.57 | ||||
| Yes | 122 (20.5%) | 7 (18.9%) | 101 (21.4%) | 14 (16.5%) | |
| No | 472 (79.5%) | 30 (81.1%) | 371 (78.6%) | 71 (73.5%) | |
| Bilateral cancer | 0.77 | ||||
| Yes | 16 (2.7%) | 1 (2.7%) | 11 (2.3%) | 4 (4.7%) | |
| No | 578 (97.3%) | 36 (97.3%) | 461 (97.7%) | 81 (95.3%) | |
| Histopathological grade | 0.014 (grade I–II vs grade III) | ||||
| Grade 1 | 103 (17.3%) | 4 (10.8%) | 82 (17.9%) | 17 (21.3%) | |
| Grade 2 | 293 (49.3%) | 14 (37.8%) | 239 (52.2%) | 40 (50.0%) | |
| Grade 3 | 179 (30.1%) | 19 (51.4%) | 137 (29.0%) | 23 (27.1%) | |
| Unknown | 19 (3.2%) | 0 (0%) | 14 (3.0%) | 5 (5.9%) | |
| ER expression | 0.000009 (negative vs positive) | ||||
| Negative (0%) | 92 (15.5%) | 16 (43.2%) | 65 (13.8%) | 11 (12.9%) | |
| Weak (1%–9%) | 18 (3.0%) | 1 (2.7%) | 15 (3.2%) | 2 (2.4%) | |
| Moderate (10%–59%) | 26 (4.4%) | 1 (2.7%) | 21 (4.4%) | 4 (4.7%) | |
| High (>59%) | 455 (76.6%) | 19 (51.4%) | 370 (78.4%) | 66 (77.6%) | |
| Unknown | 3 (0.5%) | 0 (0%) | 1 (0.2%) | 2 (2.4%) | |
| PR expression | 0.025 (negative vs positive) | ||||
| Negative (0%) | 146 (24.6%) | 16 (43.2%) | 110 (23.3%) | 20 (23.5%) | |
| Weak (1%–9%) | 81 (13.6%) | 2 (5.4%) | 68 (14.4%) | 11 (12.9%) | |
| Moderate (10%–59%) | 65 (10.9%) | 4 (10.8%) | 50 (10.6%) | 11 (12.9%) | |
| High (>59%) | 298 (50.2%) | 15 (40.5%) | 242 (51.3%) | 41 (48.2%) | |
| Unknown | 4 (0.7%) | 0 (0%) | 2 (0.4%) | 2 (2.4%) | |
| HER2 status | 0.36 | ||||
| HER2-negative | 533 (89.7%) | 33 (89.2%) | 420 (89.0%) | 80 (94.1%) | |
| HER2-positive (CISH) | 61 (10.3%) | 4 (10.8%) | 52 (11.0%) | 5 (5.9%) | |
| Ki-67 expression | 0.0012 (0%–14% vs >14%) | ||||
| Negative (<5%) | 41 (6.9%) | 2 (5.4%) | 32 (6.8%) | 7 (8.2%) | |
| Weak (5%–14%) | 268 (45.1%) | 7 (18.9%) | 220 (46.6%) | 41 (48.2%) | |
| Moderate (15%–30%) | 141 (23.7%) | 9 (24.3%) | 111 (23.5%) | 21 (24.7%) | |
| High (>30%) | 136 (22.9%) | 19 (51.4%) | 104 (22.0%) | 13 (15.3%) | |
| Unknown | 8 (1.3%) | 0 (0%) | 5 (1.0%) | 3 (3.5%) | |
| Subtype | 0.00011 | ||||
| Luminal A-like | 271 (46.2%) | 9 (24.3%) | 220 (46.6%) | 42 (49.4%) | |
| Luminal B-like (HER2-negative) | 192 (32.8%) | 11 (29.7%) | 156 (33.1%) | 25 (29.4%) | |
| Luminal B-like (HER2-positive) | 33 (5.6%) | 1 (2.7%) | 28 (5.9%) | 4 (4.7%) | |
| HER2-positive (non-luminal) | 27 (4.5%) | 3 (8.1%) | 23 (4.9%) | 1 (1.2%) | |
| Triple-negative | 63 (10.8%) | 13 (35.1%) | 40 (8.5%) | 10 (11.8%) | |
| Unknown | 8 (1.3%) | 0 (0%) | 5 (1.1%) | 3 (3.5%) | |
| Adjuvant chemotherapy | 1.5×10−9 | ||||
| Yes | 347 (58.4%) | 32 (86.5%) | 289 (61.2%) | 26 (30.6%) | |
| No | 247 (41.6%) | 5 (13.5%) | 183 (38.8%) | 59 (69.4%) | |
| Taxane-based adjuvant chemotherapy | 0.0097 | ||||
| Yes | 190 (55.1%) | 25 (78.1%) | 156 (54.4%) | 9 (34.6%) | |
| No | 146 (42.3%) | 7 (21.9%) | 122 (42.5%) | 17 (65.4%) | |
| Unknown | 9 (2.6%) | 0 (0%) | 9 (3.1%) | 0 (0%) | |
| Adjuvant radiotherapy | 5.9×10−7 | ||||
| Yes | 514 (86.5%) | 34 (91.9%) | 472 (89.4%) | 58 (68.2%) | |
| No | 80 (13.5%) | 3 (8.1%) | 50 (10.6%) | 27 (31.6%) | |
| Adjuvant endocrine therapy | 0.060 | ||||
| Yes | 391 (65.8%) | 18 (48.6%) | 319 (67.6%) | 54 (63.5%) | |
| No | 200 (33.7%) | 18 (48.6%) | 151 (32.0%) | 31 (36.5%) | |
| Unknown | 3 (0.5%) | 1 (2.7%) | 2 (0.4%) | 0 (0%) | |
CISH, chromogenic in situ hybridisation; ER, oestrogen receptor; PR, progesterone receptor.