Table 1.
Baseline characteristics of the two cohorts: patients treated without neoadjuvant systemic treatment (no systemic therapy or adjuvant systemic therapy only), and patients treated with neoadjuvant systemic treatment.
| No neoadjuvant systemic treatment (no systemic treatment or only adjuvant) (non-NST) (N = 49,631) |
Neoadjuvant systemic treatment (NST) (N = 10,154) |
|
|---|---|---|
| Year of diagnosis | ||
| 2012 | 10,593 (21.3 %) | 1341 (13.2 %) |
| 2013 | 10,243 (20.6 %) | 1688 (16.6 %) |
| 2014 | 10,023 (20.2 %) | 2024 (19.9 %) |
| 2015 | 9413 (19.0 %) | 2575 (25.4 %) |
| 2016 | 9359 (18.9 %) | 2526 (24.9 %) |
| Age (years) | ||
| Median (IQR) | 62 (52–70) | 50 (44–60) |
| <40 | 1660 (3.3 %) | 1424 (14.0 %) |
| 40-49 | 6837 (13.8 %) | 3269 (32.2 %) |
| 50-59 | 13,021 (26.2 %) | 2737 (27.0 %) |
| 60-69 | 15,324 (30.9 %) | 1889 (18.6 %) |
| 70–79 | 9440 (19.0 %) | 547 (5.4 %) |
| >79 | 3349 (6.7 %) | 288 (2.8 %) |
| Menopausal status | ||
| premenopausal | 7731 (15.6 %) | 4003 (39.4 %) |
| perimenopausal | 2354 (4.7 %) | 673 (6.6 %) |
| postmenopausal | 34,958 (70.4 %) | 4264 (42.0 %) |
| unknown | 4588 (9.2 %) | 1214 (12.0 %) |
| Socioeconomic status∗ | ||
| low | 14,531 (29.3 %) | 2651 (26.1 %) |
| medium | 19,657 (39.6 %) | 3929 (38.7 %) |
| high | 15,443 (31.1 %) | 3574 (35.2 %) |
| Mode of detection | ||
| Clinically detected | 25,747 (51.9 %) | 8352 (82.3 %) |
| Screen-detected | 23,355 (47.1 %) | 1544 (15.2 %) |
| unknown | 529 (1.1 %) | 258 (2.5 %) |
| Laterality | ||
| left | 25,212 (50.8 %) | 5276 (52.0 %) |
| right | 24,416 (49.2 %) | 4878 (48.0 %) |
| unknown | 3 (0.0 %) | – |
| Sublocalisation | ||
| outer quadrants (C50.4–6) | 23,515 (47.4 %) | 4524 (44.6 %) |
| inner quadrants (C50.2–3) | 10,118 (20.4 %) | 1635 (16.1 %) |
| central parts (C50.0–1) | 3858 (7.8 %) | 748 (7.4 %) |
| overlapping lesions (C50.8) | 11,474 (23.1 %) | 3139 (30.9 %) |
| unknown | 666 (1.3 %) | 108 (1.1 %) |
| Histological tumour type | ||
| ductal | 40,321 (81.2 %) | 8609 (84.8 %) |
| lobular | 5570 (11.2 %) | 1046 (10.3 %) |
| mixed ductal lobular | 1425 (2.9 %) | 233 (2.3 %) |
| other | 2315 (4.7 %) | 266 (2.6 %) |
| Differentiation grade | ||
| grade 1 | 12,865 (25.9 %) | 790 (7.8 %) |
| grade 2 | 22,829 (46.0 %) | 3102 (30.5 %) |
| grade 3 | 12,449 (25.1 %) | 2378 (23.4 %) |
| unknown | 1488 (3.0 %) | 3884 (38.3 %) |
| Multifocality | ||
| no | 42,343 (85.3 %) | 7312 (72.0 %) |
| yes | 7112 (14.3 %) | 2727 (26.9 %) |
| unknown | 176 (0.4 %) | 115 (1.1 %) |
| Clinical tumour stage | ||
| cTIS | 1119 (2.3 %) | – |
| cT1 | 32,918 (66.3 %) | 1553 (15.3 %) |
| cT2 | 12,898 (26.0 %) | 5870 (57.8 %) |
| cT3 | 1195 (2.4 %) | 1959 (19.3 %) |
| cT4 | 253 (0.5 %) | 772 (7.6 %) |
| unknown | 1248 (2.5 %) | - |
| Clinical nodal stage | ||
| cN0 | 44,726 (90.1 %) | 4226 (41.6 %) |
| cN1 | 4401 (8.9 %) | 5024 (49.5 %) |
| cN2 | 65 (0.1 %) | 203 (2.0 %) |
| cN3 | 68 (0.1 %) | 701 (6.9 %) |
| unknown | 371 (0.7 %) | – |
| Pathological tumour classification | ||
| pT0 | – | 2358 (23.2 %) |
| pTIS | – | 410 (4.0 %) |
| pT1 | 34,677 (69.9 %) | 4052 (39.9 %) |
| pT2 | 13,502 (27.2 %) | 2351 (23.2 %) |
| pT3 | 1213 (2.4 %) | 632 (6.2 %) |
| pT4 | 239 (0.5 %) | 116 (1.1 %) |
| unknown | – | 235 (2.3 %) |
| Pathological nodal classification | ||
| pN0 | 35,116 (70.8 %) | 5284 (52.0 %) |
| pN1 | 11,944 (24.1 %) | 3234 (31.8 %) |
| pN2 | 1631 (3.3 %) | 818 (8.1 %) |
| pN3 | 940 (1.9 %) | 372 (3.7 %) |
| unknown | – | 446 (4.4 %) |
| Hormonal receptor status + treatment | ||
| positive∗∗ + endocrine therapy | 26,610 (53.6 %) | 6823 (67.2 %) |
| positive∗∗ – endocrine therapy | 16,270 (32.8 %) | 364 (3.6 %) |
| negative | 6267 (12.6 %) | 2858 (28.1 %) |
| unknown | 484 (1.0 %) | 109 (1.1 %) |
| HER2 status + treatment | ||
| negative | 43,032 (86.7 %) | 7438 (73.3 %) |
| positive + targeted therapy | 3665 (7.4 %) | 2445 (24.1 %) |
| positive – targeted therapy | 1581 (3.2 %) | 66 (0.7 %) |
| unknown∗∗∗ | 1353 (2.7 %) | 205 (2.0 %) |
| Ductal carcinoma in situ present | ||
| no | 23,843 (48.0 %) | 6214 (61.2 %) |
| yes | 25,167 (50.7 %) | 3612 (35.6 %) |
| unknown | 621 (1.3 %) | 328 (3.2 %) |
| Molecular diagnostics∗∗∗∗ | ||
| no | 44,630 (89.9 %) | 9903 (97.5 %) |
| yes, low risk | 2990 (6.0 %) | 97 (1.0 %) |
| yes, high risk | 1767 (3.6 %) | 142 (1.4 %) |
| yes, unknown result | 244 (0.5 %) | 12 (0.1 %) |
| Type of surgery + RT + immediate breast reconstruction | ||
| BCS + RT | 31,692 (63.9 %) | 4947 (48.7 %) |
| BCS – RT | 689 (1.4 %) | 153 (1.5 %) |
| mastectomy + RT – immediate breast reconstruction | 4008 (8.1 %) | 2718 (26.8 %) |
| mastectomy + RT + immediate breast reconstruction | 682 (1.4 %) | 667 (6.6 %) |
| mastectomy – RT – immediate breast reconstruction | 9420 (19.0 %) | 876 (8.6 %) |
| mastectomy – RT + immediate breast reconstruction | 3140 (6.3 %) | 793 (7.8 %) |
| Axillary lymph node dissection | ||
| no | 42,072 (84.8 %) | 6454 (63.6 %) |
| yes | 7559 (15.2 %) | 3700 (36.4 %) |
| Chemotherapy | ||
| no | 33,078 (66.6 %) | 863 (8.5 %) |
| yes | 16,553 (33.4 %) | 9291 (91.5 %) |
| Pathologic complete response | ||
| no | NA | 7527 (74.1 %) |
| yes | NA | 2215 (21.8 %) |
| unknown | NA | 412 (4.1 %) |
| Vital status at end of follow-up | ||
| alive | 42,007 (84.6 %) | 8385 (82.6 %) |
| deceased (all causes) | 7624 (15.4 %) | 1769 (17.4 %) |
| Locoregional recurrence as first event | ||
| no | 48,541 (97.8 %) | 9820 (96.7 %) |
| yes | 1090 (2.2 %) | 334 (3.3 %) |
| Contralateral breast tumour as first event | ||
| no | 48,065 (96.8 %) | 9955 (98.0 %) |
| yes | 1566 (3.2 %) | 199 (2.0 %) |
∗SES was based on scores assigned to the four numbers of the Dutch postal code, extracted from the Netherlands Institute for Social Research.∗∗either ER or PR positive or both. ∗∗∗includes 2+ result of immunohistochemistry (0.3 %). ∗∗∗∗either oncotype DX or mammaprint. intermediate risk oncotype (<0.1 %) classified as low risk.
Abbreviations: NST = neoadjuvant systemic treatment, IQR = interquartile range, p = pathological (post-operative), T = tumour, N = nodal, IS = in situ, HER2 = human epidermal growth factor receptor 2, NA = not applicable, BCS = breast-conserving surgery, RT = radiation therapy.