Abstract
Purpose
Materials and Methods
Results
Electronic Supplementary Material
Notes
Ethical Statement
The study was approved by the Institutional Review Board of Seoul National University Hospital (IRB No. 2301-164-1403), and the need for informed consent was waived.
Author Contributions
Conceived and designed the analysis: Kim K, Shin KH.
Collected the data: Chun SJ, Jo JH, Kim YB, Park S, Ahn SJ, Kim SS, Shin KH.
Contributed data or analysis tools: Chun SJ, Kim K, Shin KH.
Performed the analysis: Chun SJ, Kim K.
Wrote the paper: Chun SJ, Jo JH, Kim YB, Park S, Ahn SJ, Kim SS, Kim K, Shin KH.
References
Table 1.
ABS | ASBS | ASTRO (‘suitable’) | ASTRO (‘cautionary’) | GEC-ESTRO (‘low-risk’) | GEC-ESTRO (‘intermediate-risk’) | |
---|---|---|---|---|---|---|
Age (yr) | ≥ 45 | ≥ 45 | ≥ 50 | ≥ 40 | > 50 | > 40, ≤ 50 |
Histology | All invasive | All invasive | All invasive, but not ILC | All invasive, including ILCa) | IDC, mucinous, tubular, medullary, colloid | IDC, ILC, mucinous, tubular, medullary, colloid |
Tumor size (cm) | ≤ 3 (total) | ≤ 3 (total) | ≤ 2 (tumor) | 2-3 (tumor)a) | ≤ 3 (tumor size) | ≤ 3 (tumor size) |
≤ 3 (total) | ≤ 3 (total) | |||||
Lymph node | pN0 | pN0 | pN0 | pN0 | pN0 | pN0 |
Margin | Negative | Negative | ≥ 2 mm | Close (< 2 mm)a) | ≥ 2 mm | Close (< 2 mm) |
LVSI | No | No | No | Yesa) | No | No |
ER | Any | Any | Positive | Negativea) | Any | Any |
HER2 | Negative | Any | Any | Any | Any | Any |
EIC | Any | Any | No | ≤ 3 cma) | No | No |
Focality | Unifocal | Any | Unifocal | Unifocalb) | Unifocal | Any |
ABS, American Brachytherapy Society; ASBS, American Society of Breast Surgeons; ASTRO, American Society for Radiation Oncology; EIC, extensive intraductal component; ER, estrogen receptor; GEC-ESTRO, Groupe Européen de Curiethérapie and the European Society for Radiotherapy and Oncology; HER2, human epidermal growth factor receptor 2; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; LVSI, lymphovascular invasion.
Table 2.
Variable | Total patients (n=1,251) | WBI (n=1,055) | APBI (n=196) | p-value |
---|---|---|---|---|
Age (yr) | ||||
< 45 | 218 (17.4) | 216 (20.5) | 2 (1.0) | < 0.001 |
45-50 | 277 (22.1) | 248 (23.5) | 29 (14.8) | |
> 50 | 756 (60.4) | 591 (56.0) | 165 (84.2) | |
Laterality | ||||
Left | 621 (49.6) | 525 (49.8) | 96 (49.0) | 0.902 |
Right | 630 (50.4) | 530 (50.2) | 100 (51.0) | |
Axillary surgery | ||||
SLNBx | 1,222 (97.7) | 1,029 (97.5) | 193 (98.5) | 0.499 |
ALND | 25 (2.0) | 23 (2.2) | 2 (1.0) | |
Not done | 4 (0.3) | 3 (0.3) | 1 (0.5) | |
Histology | ||||
IDC | 1,155 (92.3) | 982 (93.1) | 173 (88.3) | < 0.001 |
ILC | 44 (3.5) | 40 (3.8) | 4 (2.0) | |
Others | 52 (4.2) | 33 (3.1) | 19 (9.7) | |
Size (invasive tumor only) (cm) | ||||
≤ 2 | 973 (77.8) | 794 (75.3) | 179 (91.3) | < 0.001 |
> 2 and ≤ 3 | 234 (18.7) | 218 (20.7) | 16 (8.2) | |
> 3 | 44 (3.5) | 43 (4.1) | 1 (0.5) | |
Size (including DCIS) (cm) | ||||
≤ 2 | 788 (63.0) | 620 (58.8) | 168 (85.7) | < 0.001 |
> 2 and ≤ 3 | 307 (24.5) | 282 (26.7) | 25 (12.8) | |
> 3 | 156 (12.5) | 153 (14.5) | 3 (1.5) | |
EIC | ||||
Positive | 322 (25.7) | 294 (27.9) | 28 (14.3) | < 0.001 |
Negative | 883 (70.6) | 727 (68.9) | 156 (79.6) | |
N/A | 46 (3.7) | 34 (3.2) | 12 (6.1) | |
Focality | ||||
Unifocal | 1,082 (86.5) | 902 (85.5) | 180 (91.8) | 0.023 |
Multifocal | 169 (13.5) | 153 (14.5) | 16 (8.2) | |
Centricity | ||||
Unicentric | 1,245 (99.5) | 1,049 (99.4) | 196 (100) | 0.620 |
Multicentric | 6 (0.5) | 6 (0.6) | 0 | |
Resection margin | ||||
Positive | 74 (5.9) | 73 (6.9) | 1 (0.5) | < 0.001 |
Close (< 2 mm) | 436 (34.9) | 404 (38.3) | 32 (16.3) | |
Negative (≥ 2 mm) | 615 (49.2) | 495 (46.9) | 120 (61.2) | |
N/Aa) | 126 (10.1) | 83 (7.9) | 43 (21.9) | |
LVSI | ||||
Positive | 129 (10.3) | 127 (12.0) | 2 (1.0) | < 0.001 |
Negative | 1,122 (89.7) | 928 (88.0) | 194 (99.0) | |
ER status | ||||
Positive | 1,000 (79.9) | 806 (76.4) | 194 (99.0) | < 0.001 |
Negative | 251 (20.1) | 249 (23.6) | 2 (1.0) | |
HER2 status | ||||
Positive | 153 (12.2) | 151 (14.3) | 2 (1.0) | < 0.001 |
Negative | 1,097 (87.7) | 903 (85.6) | 194 (99.0) | |
N/A | 1 (0.1) | 1 (0.1) | 0 | |
Ki-67 (%) | ||||
< 20 | 803 (64.2) | 622 (59.0) | 181 (92.3) | < 0.001 |
≥ 20 | 445 (35.6) | 430 (40.8) | 15 (7.7) | |
N/A | 3 (0.2) | 3 (0.3) | 0 | |
Adjuvant chemotherapy | ||||
Yes | 426 (34.1) | 409 (38.8) | 17 (8.7) | < 0.001 |
No | 825 (65.9) | 646 (61.2) | 179 (91.3) | |
Adjuvant endocrine therapy | ||||
Yes (TMX) | 535 (42.8) | 481 (45.6) | 54 (27.6) | < 0.001 |
Yes (AI) | 421 (33.7) | 311 (29.5) | 110 (56.1) | |
No | 295 (23.6) | 263 (24.9) | 32 (16.3) |
Values are presented as number (%). AI, aromatase inhibitor; ALND, axillary lymph node dissection; APBI, accelerated partial breast irradiation; DCIS, ductal carcinoma in situ; EIC, extensive intraductal component; ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; LVSI, lymphovascular space invasion; N/A, not available; SLNBx, sentinel lymph node biopsy; TMX, tamoxifen; WBI, whole breast irradiation.
Table 3.
Criteria | Total patients (n=1,251) | WBI (n=1,055) | APBI (n=196) | Actual APBI rates |
---|---|---|---|---|
ASTROa) | ||||
Suitable | 158 (13.7) | 72 (7.2) | 86 (55.1) | 86/158 (54.4) |
Cautionary | 610 (52.9) | 548 (54.9) | 62 (39.7) | 62/610 (10.2) |
Unsuitable | 386 (33.4) | 378 (37.9) | 8 (5.1) | 8/386 (2.1) |
GEC-ESTROa) | ||||
Low-risk | 242 (21.0) | 152 (15.2) | 90 (58.4) | 90/242 (37.2) |
Intermediate-risk | 385 (33.3) | 352 (35.2) | 33 (21.4) | 33/385 (8.6) |
High-risk | 527 (45.7) | 496 (49.6) | 31 (20.1) | 31/527 (5.9) |
ABS | ||||
Acceptable | 632 (50.5) | 461 (43.7) | 171 (87.2) | 171/632 (27.1) |
Unacceptable | 619 (49.5) | 594 (56.3) | 25 (12.8) | 25/619 (4.0) |
ASBS | ||||
Recommended | 794 (63.5) | 606 (57.4) | 188 (95.9) | 188/794 (23.7) |
Not recommended | 457 (36.5) | 449 (42.6) | 8 (4.1) | 8/457 (1.8) |
Values are presented as number (%). ABS, American Brachytherapy Society; APBI, accelerated partial breast irradiation; ASBS, American Society of Breast Surgeons; ASTRO, American Society for Radiation Oncology; GEC-ESTRO, Groupe Européen de Curiethérapie and the European Society for Radiotherapy and Oncology; WBI, whole breast irradiation.