Introduction
Materials and methods
Study population
Variable | SEARCH | ||
---|---|---|---|
Mean age (range) | 52.6 (24 to 73) | ||
Mean follow-up in years (range) | 8.5 (0.37 to 18.6) | ||
Number of breast cancer deaths (%) | 563 (14) | ||
Five-year survival % | 90 | ||
Categories | Number | Percent | |
Grade | 1 | 768 | 19 |
2 | 1, 622 | 39 | |
3 | 1, 020 | 25 | |
Missing | 715 | 17 | |
Node status | Negative | 2, 309 | 56 |
Positive | 1, 424 | 35 | |
Missing | 392 | 10 | |
Tumour size | < 2 cm | 2, 208 | 54 |
2 to 4.9 cm | 1, 522 | 37 | |
≥5 cm | 145 | 4 | |
Missing | 250 | 6 | |
Endocrine therapy | No | 770 | 19 |
Yes | 3, 315 | 80 | |
Missing | 40 | 1 | |
Chemotherapy | No | 2, 692 | 65 |
Yes | 1, 392 | 34 | |
Missing | 41 | 1 | |
ER status | Negative | 772 | 19 |
Positive | 2, 287 | 55 | |
Missing | 1, 066 | 26 | |
PR status | Negative | 889 | 22 |
Positive | 2, 194 | 53 | |
Missing | 1, 042 | 25 | |
HER2 status | Negative | 2, 560 | 62 |
Positive | 349 | 8 | |
Missing | 1, 216 | 29 | |
Molecular subtype | Luminal 1a | 1, 631 | 40 |
Luminal 1b | 215 | 5 | |
Luminal 2 | 202 | 5 | |
HER2 | 120 | 3 | |
CBP | 214 | 5 | |
5NP | 130 | 3 | |
Missing | 1, 613 | 39 |
Immunohistochemistry and scoring
Definition of molecular subtype
Statistical analyses
Missing data
Results
CSC markers have distinct expression patterns in normal and neoplastic breast tissue
Variable | Marker | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
CD44+CD24-/low | CD44-CD24+ | CD44+CD24+ | ALDH1A1 | Stromal ALDH1A1 | ALDH1A3 | Stromal ALDH1A3 | ITGA6 | Score | Total CSCs | ||
Allred score | 0 | 1, 808 (44) | 814 (20) | 1, 994 (48) | 2, 452 (59) | 1, 112 (27) | 1, 763 (43) | 2, 245 (54) | 2, 004 (49) | 0 | 1, 147 (28) |
2 | 27 (1) | 18 (< 1) | 34 (1) | 169 (4) | 303 (7) | 43 (1) | 12 (< 1) | 20 (< 1) | 1 | 401 (10) | |
3 | 96 (2) | 241 (6) | 74 (2) | 95 (2) | 485 (12) | 183 (4) | 86 (2) | 106 (3) | 2 | 75 (2) | |
4 | 103 (3) | 318 (8) | 174 (4) | 69 (2) | 442 (11) | 162 (4) | 102 (2) | 77 (2) | 3 | 18 (< 1) | |
5 | 136 (3) | 310 (8) | 112 (3) | 40 (1) | 230 (6) | 120 (3) | 73 (2) | 50 (1) | 4 | 5 (< 1) | |
6 | 103 (3) | 358 (9) | 52 (1) | 27 (1) | 156 (4) | 194 (5) | 64 (2) | 39 (1) | Missing | 2, 479 (60) | |
7 | 104 (3) | 375 (9) | 74 (2) | 20 (< 1) | 130 (3) | 119 (3) | 27 (1) | 49 (1) | |||
8 | 160 (4) | 103 (3) | 23 (1) | 18 (< 1) | 32 (1) | 27 (1) | 2 (< 1) | 44 (1) | |||
Missing | 1, 588 (39) | 1, 588 (39) | 1, 588 (39) | 1, 235 (30) | 1, 235 (30) | 1, 514 (37) | 1, 514 (37) | 1, 736 (42) | |||
Cut-off | > 4 | > 3 | > 2 | > 4 | > 2 | > 6 | > 3 | > 4 | NA | ||
Status* | Negative | 2, 034 (80) | 1, 073 (42) | 2, 028 (80) | 2, 785 (96) | 1, 415 (49) | 2, 465 (94) | 2, 343 (90) | 2, 207 (92) | ||
Positive | 503 (20) | 1, 464 (58) | 509 (20) | 105 (4) | 1, 475 (51) | 146 (6) | 268 (10) | 182 (8) |
Association with clinical and molecular characteristics
ER POSITIVE | ER NEGATIVE | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Variable | CD44+CD24-/low | ALDH1A1 | ALDH1A3 | ITGA6 | CD44+CD24-/low | ALDH1A1 | ALDH1A3 | ITGA6 | |||||||||
Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | ||
Morphology | Ductal | 1, 030 (73) | 241 (81) | 1, 357 (73) | 38 (83) | 1, 242 (73) | 52 (75) | 1, 116 (74) | 41 (71) | 369 (88) | 125 (83) | 491 (85) | 45 (90) | 434 (85) | 60 (90) | 373 (86) | 83 (85) |
Lobular | 246 (17) | 34 (11) | 315 (17) | 3 (7) | 277 (16) | 11 (16) | 241 (16) | 11 (19) | 20 (5) | 6 (4) | 32 (5) | 0 (0) | 25 (5) | 3 (4) | 23 (5) | 4 (4) | |
Other | 140 (10) | 23 (8) | 188 (10) | 5 (11) | 176 (10) | 6 (9) | 142 (9) | 6 (10) | 32 (8) | 19 (13) | 58 (10) | 5 (10) | 52 (10) | 4 (6) | 37 (9) | 11 (11) | |
P-value | 0.012 | 0.172 | 0.892 | 0.803 | 0.169 | 0.238* | 0.625* | 0.645* | |||||||||
Grade | 1 | 283 (23) | 78 (33) | 402 (25) | 3 (11) | 356 (25) | 10 (19) | 304 (24) | 10 (26) | 23 (6) | 1 (1) | 32 (6) | 0 (0) | 29 (7) | 1 (2) | 22 (6) | 2 (3) |
2 | 684 (56) | 112 (47) | 873 (55) | 13 (46) | 787 (55) | 28 (53) | 700 (55) | 20 (51) | 103 (28) | 28 (23) | 145 (29) | 7 (21) | 119 (27) | 11 (24) | 109 (29) | 15 (19) | |
3 | 251 (21) | 49 (21) | 315 (20) | 12 (43) | 297 (21) | 15 (28) | 260 (21) | 9 (23) | 242 (66) | 93 (76) | 321 (64) | 27 (79) | 295 (67) | 33 (73) | 242 (65) | 60 (78) | |
P-value | 0.006 | 0.012* | 0.335 | 0.874 | 0.012* | 0.164* | 0.538* | 0.086* | |||||||||
Node status | Negative | 783 (60) | 184 (68) | 1064 (61) | 23 (53) | 972 (62) | 41 (63) | 859 (62) | 34 (63) | 203 (51) | 84 (64) | 310 (57) | 19 (41) | 268 (56) | 34 (54) | 206 (52) | 55 (62) |
Positive | 533 (40) | 86 (32) | 669 (39) | 20 (47) | 602 (38) | 24 (37) | 528 (38) | 20 (37) | 195 (49) | 48 (36) | 231 (43) | 27 (59) | 207 (44) | 29 (46) | 194 (48) | 34 (38) | |
P-value | 0.008 | 0.293 | 0.830 | 0.878 | 0.012 | 0.036 | 0.712 | 0.078 | |||||||||
Tumour size | < 2 cm | 788 (58) | 182 (64) | 1050 (59) | 22 (49) | 964 (59) | 37 (55) | 842 (59) | 30 (52) | 176 (44) | 61 (43) | 236 (43) | 23 (48) | 208 (43) | 23 (37) | 167 (41) | 38 (44) |
2 to 4.9 cm | 545 (40) | 88 (31) | 695 (39) | 22 (49) | 628 (38) | 28 (42) | 551 (38) | 27 (47) | 208 (52) | 74 (52) | 289 (53) | 23 (48) | 259 (54) | 36 (58) | 225 (55) | 45 (52) | |
≥5 cm | 33 (2) | 13 (5) | 50 (3) | 1 (2) | 44 (3) | 2 (3) | 44 (3) | 1 (2) | 14 (4) | 6 (4) | 24 (4) | 2 (4) | 16 (3) | 3 (5) | 20 (5) | 3 (3) | |
P-value | 0.005 | 0.362* | 0.747* | 0.469* | 0.916 | 0.777* | 0.519* | 0.821* |
ER POSITIVE | ER NEGATIVE | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Variable | CD44+CD24-/low | ALDH1A1 | ALDH1A3 | ITGA6 | CD44+CD24-/low | ALDH1A1 | ALDH1A3 | ITGA6 | |||||||||
Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | Negative | Positive | ||
Molecular subtype | Luminal 1a | 1050 (83) | 205 (75) | 1, 331 (81) | 28 (72) | 1, 232 (81) | 40 (59) | 1, 045 (80) | 41 (82) | 60 (17) | 9 (7) | 75 (16) | 2 (4) | 71 (17) | 2 (4) | 62 (17) | 8 (10) |
Other | 219 (17) | 69 (25) | 307 (19) | 11 (28) | 283 (19) | 28 (41) | 257 (20) | 9 (18) | 292 (83) | 120 (93) | 408 (84) | 43 (96) | 359 (83) | 54 (96) | 294 (83) | 69 (90) | |
P-value | 0.002 | 0.136 | < 0.001 | 0.761 | 0.005 | 0.046* | 0.009* | 0.129 | |||||||||
Luminal 1b | 96 (8) | 49 (18) | 156 (10) | 6 (15) | 152 (10) | 11 (16) | 128 (10) | 4 (8) | 12 (3) | 5 (4) | 17 (4) | 2 (4) | 15 (3) | 2 (4) | 8 (2) | 5 (6) | |
Other | 1173 (92) | 225 (82) | 1482 (90) | 33 (85) | 1363 (90) | 57 (84) | 1174 (90) | 46 (92) | 340 (97) | 124 (96) | 466 (96) | 43 (96) | 415 (97) | 54 (96) | 348 (98) | 72 (94) | |
P-value | < 0.001 | 0.221 | 0.103 | 0.812* | 0.806 | 0.672* | 1.000* | 0.062* | |||||||||
Luminal 2 | 123 (10) | 20 (7) | 151 (9) | 5 (13) | 131 (9) | 17 (25) | 129 (10) | 5 (10) | 13 (4) | 3 (2) | 16 (3) | 2 (4) | 14 (3) | 2 (4) | 16 (4) | 1 (1) | |
Other | 1, 146 (90) | 254 (93) | 1, 487 (91) | 34 (87) | 1, 384 (91) | 51 (75) | 1, 173 (90) | 45 (90) | 339 (96) | 126 (98) | 467 (97) | 43 (96) | 416 (97) | 54 (96) | 340 (96) | 76 (99) | |
P-value | 0.215 | 0.444 | < 0.001 | 0.983 | 0.576* | 0.660* | 0.705* | 0.329* | |||||||||
HER2 | NA | NA | NA | NA | 81 (23) | 14 (11) | 86 (18) | 17 (38) | 83 (19) | 14 (25) | 76 (21) | 12 (16) | |||||
Other | 271 (77) | 115 (89) | 397 (82) | 28 (62) | 347 (81) | 42 (75) | 280 (79) | 65 (84) | |||||||||
P-value | 0.003 | 0.001 | 0.316 | 0.254 | |||||||||||||
CBP | NA | NA | NA | NA | 118 (34) | 68 (53) | 180 (37) | 18 (40) | 164 (38) | 23 (41) | 122 (34) | 35 (45) | |||||
Other | 234 (66) | 61 (47) | 303 (63) | 27 (60) | 266 (62) | 33 (59) | 234 (66) | 42 (55) | |||||||||
P-value | < 0.001 | 0.717 | 0.671 | 0.064 | |||||||||||||
5NP | NA | NA | NA | NA | 68 (19) | 30 (23) | 109 (23) | 4 (9) | 83 (19) | 13 (23) | 72 (20) | 16 (21) | |||||
Other | 284 (81) | 99 (77) | 374 (77) | 41 (91) | 347 (81) | 43 (77) | 284 (80) | 61 (79) | |||||||||
P-value | 0.342 | 0.035* | 0.489 | 0.913 | |||||||||||||
Ki67 | Negative | 1, 037 (77) | 220 (77) | 1, 370 (78) | 27 (66) | 1, 243 (78) | 41 (61) | 1, 088 (78) | 37 (70) | 196 (50) | 52 (37) | 262 (49) | 13 (27) | 232 (48) | 23 (39) | 200 (50) | 30 (34) |
Positive | 305 (23) | 65 (23) | 386 (22) | 14 (34) | 360 (22) | 26 (39) | 308 (22) | 16 (30) | 197 (50) | 90 (63) | 276 (51) | 36 (73) | 255 (52) | 36 (61) | 198 (50) | 58 (66) | |
P-value | 0.977 | 0.064 | 0.002 | 0.163 | 0.007 | 0.003 | 0.208 | 0.006 |
CSC markers predict poor outcome in ER- disease
Variable | Complete case analysis | Multiple imputation (M = 50) | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
n | HR (95% CI) |
P
| T (95% CI) |
P
| n | HR (95% CI) |
P
| T (95% CI) |
P
| |
Grade | 481 | 3.6 (1.3 to 9.7) | 0.011 | 0.32 (0.16 to 0.61) | 0.001 | 1, 070 | 3.9 (1.8 to 8.3) | < 0.001 | 0.42 (0.25 to 0.68) | < 0.001 |
Node status | 4.1 (2.6 to 6.3) | < 0.001 | NA | 2.8 (2.1 to 3.9) | < 0.001 | NA | ||||
Tumour size | * | NA | 1.5 (1.1 to 1.9) | 0.002 | NA | |||||
PR + | 0.25 (0.13 to 0.50) | < 0.001 | NA | 0.16 (0.03 to 0.69) | 0.015 | 2.1 (0.78 to 5.4) | 0.146 | |||
HER2+ | * | NA | 1.4 (0.99 to 2.0) | 0.060 | NA | |||||
ALDH1A1 +
|
2.3 (1.3 to 4.0)
|
0.004
|
NA
|
1.4 (0.83 to 2.5)
|
0.191
|
NA
| ||||
Grade | 401 | 3.0 (0.99 to 9.0) | 0.052 | 0.39 (0.18 to 0.82) | 0.013 | 1, 070 | 4.2 (2.0 to 8.9) | < 0.001 | 0.40 (0.24 to 0.64) | < 0.001 |
Node status | 4.2 (2.6 to 6.7) | < 0.001 | NA | 2.9 (2.1 to 4.0) | < 0.001 | NA | ||||
Tumour size | * | NA | 1.5 (1.1 to 1.9) | 0.003 | NA | |||||
PR + | 0.23 (0.11 to 0.49) | < 0.001 | NA | 0.42 (0.26 to 0.69) | 0.001 | NA | ||||
HER2+ | * | NA | 1.4 (1.0 to 2.0) | 0.034 | NA | |||||
ITGA6 +
|
7.5 (2.6 to 21.6)
|
< 0.001
|
0.18 (0.06 to 0.54)
|
0.002
|
2.8 (1.2 to 6.3)
|
0.013
|
0.50 (0.24 to 1.0)
|
0.055
| ||
Grade | 298 | 3.8 (1.1 to 13.0) | 0.036 | 0.30 (0.13 to 0.68) | 0.004 | 1, 070 | 4.0 (1.8 to 8.5) | < 0.001 | 0.41 (0.25 to 0.67) | < 0.001 |
Node status | 4.2 (2.4 to 7.4) | < 0.001 | NA | 2.9 (2.1 to 4.0) | < 0.001 | NA | ||||
Tumour size | * | NA | 1.5 (1.1 to 1.9) | 0.003 | NA | |||||
PR + | 0.15 (0.05 to 0.44) | < 0.001 | NA | 0.43 (0.26 to 0.70) | 0.001 | NA | ||||
HER2 + | * | NA | 1.4 (1.0 to 2.0) | 0.037 | NA | |||||
Endocrine therapy | 1.7 (0.98 to 2.9) | 0.057 | NA | * | NA | |||||
Total CSCs (0-3)
|
1.7 (1.3 to 2.4)
|
< 0.001
|
NA
|
1.8 (1.2 to 2.6)
|
0.002
|
0.71 (0.51 to 0.99)
|
0.042
|
Marker | Follow-up (years) | |||||||
---|---|---|---|---|---|---|---|---|
0 to 2 | P-value | 2 to 4 | P-value | 4 to 6 | P-value | 6 to 10 | P-value | |
ITGA6 | 2.4 (1.2 to 5.0) | 0.019 | 1.4 (0.72 to 2.7) | 0.329 | 0.60 (0.17 to 2.1) | 0.429 | 0.68 (0.15 to 3.1) | 0.612 |
Total CSCs | 1.6 (1.1 to 2.3) | 0.007 | 1.4 (1.0 to 1.9) | 0.050 | 1.0 (0.60 to 1.7) | 0.994 | 0.86 (0.43 to 1.7) | 0.666 |