Table 2. Association between clinical characteristics and case status (incident or prevalent breast cancer), using the Chi-square test.
| Total N = 7,768 |
Case-type | P-value a | ||
|---|---|---|---|---|
| Incident N = 3,316 |
Prevalent N = 4,452 |
|||
| Tumour characteristics | ||||
| Tumour behaviour | ||||
| In-situ | 1,113 (14) | 406 (12) | 707 (16) | 0.012 |
| Invasive | 5,891 (76) | 2,388 (72) | 3,503 (79) | |
| Unknown | 764 (10) | 522 (16) | 242 (5) | |
| Tumour histology type | ||||
| Ductal | 6,133 (79) | 2,390 (72) | 3,743 (84) | <0.001 |
| Lobular | 304 (4) | 137 (4) | 167 (4) | |
| Mucinous | 211 (3) | 90 (3) | 121 (3) | |
| Others | 356 (5) | 177 (5) | 179 (4) | |
| Unknown | 764 (10) | 522 (16) | 242 (5) | |
| Nodal status | ||||
| Negative | 4,763 (61) | 1,973 (59) | 2,790 (63) | <0.001 |
| Positive | 2,577 (33) | 1,176 (35) | 1,401 (31) | |
| Unknown | 428 (6) | 167 (5) | 261 (6) | |
| Tumour size | ||||
| T0 | 1,108 (14) | 411 (12) | 697 (16) | <0.001 |
| T1 | 2,932 (38) | 1,137 (34) | 1,795 (40) | |
| T2 | 2,535 (33) | 1,185 (36) | 1,350 (30) | |
| T3 | 406 (5) | 198 (6) | 208 (5) | |
| T4 | 307 (4) | 164 (5) | 143 (3) | |
| Unknown | 480 (6) | 221 (7) | 259 (6) | |
| Tumour stage | ||||
| 0 | 1,111 (14) | 411 (12) | 700 (16) | <0.001 |
| I | 2,182 (28) | 847 (26) | 1,335 (30) | |
| II | 2,678 (34) | 1,212 (37) | 1,466 (33) | |
| III | 1,163 (15) | 542 (16) | 621 (14) | |
| IV | 272 (4) | 141 (4) | 131 (3) | |
| Unknown | 362 (5) | 163 (5) | 199 (4) | |
| Tumour grade | ||||
| Well differentiated | 1,174 (15) | 446 (13) | 728 (16) | 0.005 |
| Moderate differentiated | 2,788 (36) | 1,170 (35) | 1,618 (36) | |
| Poor differentiated | 2,858 (37) | 1,246 (38) | 1,612 (36) | |
| Unknown | 948 (12) | 454 (14) | 494 (11) | |
| Estrogen receptor | ||||
| Positive | 5,005 (64) | 2,271 (68) | 2,734 (61) | 0.392 |
| Negative | 1,549 (20) | 683 (21) | 866 (19) | |
| Unknown | 1,214 (16) | 362 (11) | 852 (19) | |
| Progesterone receptor | ||||
| Positive | 4,411 (57) | 2,012 (61) | 2,399 (54) | 0.051 |
| Negative | 2,084 (27) | 896 (27) | 1,188 (27) | |
| Unknown | 1,273 (16) | 408 (12) | 865 (19) | |
| Human epidermal growth factor receptor 2 | ||||
| Positive | 1,504 (19) | 761 (23) | 743 (17) | 0.009 |
| Negative | 3,797 (49) | 1,768 (53) | 2,029 (46) | |
| Unknown | 2,467 (32) | 787 (24) | 1,680 (38) | |
| Treatment | ||||
| Breast surgery | ||||
| Yes | 7,132 (92) | 3,089 (93) | 4,043 (91) | 0.006 |
| No | 166 (2) | 90 (3) | 76 (2) | |
| Unknown | 470 (6) | 137 (4) | 333 (7) | |
| Radiotherapy | ||||
| Yes | 4,038 (52) | 1,702 (51) | 2,336 (52) | 0.015 |
| No | 2,877 (37) | 1,298 (39) | 1,579 (35) | |
| Unknown | 853 (11) | 316 (10) | 537 (12) | |
| Neo-adjuvant chemotherapy | ||||
| Yes | 721 (9) | 440 (13) | 281 (6) | <0.001 |
| No | 5,066 (65) | 1,984 (60) | 3,082 (69) | |
| Unknown | 1,981 (26) | 892 (27) | 1,089 (24) | |
| Adjuvant chemotherapy | ||||
| Yes | 3,861 (50) | 1,551 (47) | 2,310 (52) | 0.069 |
| No | 2,489 (32) | 1,058 (32) | 1,431 (32) | |
| Unknown | 1,418 (18) | 707 (21) | 711 (16) | |
| Endocrine therapy | ||||
| Yes | 4,604 (59) | 1,863 (56) | 2,741 (62) | 0.577 |
| No | 1,790 (23) | 710 (21) | 1,080 (24) | |
| Unknown | 1,374 (18) | 743 (22) | 631 (14) | |
| Targeted therapy | ||||
| Yes | 621 (8) | 271 (8) | 350 (8) | 0.072 |
| No | 4,031 (52) | 1,602 (48) | 2,429 (55) | |
| Unknown | 3,116 (40) | 1,443 (44) | 1,673 (38) | |
Column percentages are presented.
a Differences between incidence and prevalence cases were assessed using chi square testing.