Table 1. Comparison of patient, tumour, and treatment characteristics among the four broad ethnic groups of women aged 18–39 years with breast cancer.
| Characteristic | Non-Hispanic white (n=35 101) | Black (n=8215) | Hispanic white (n=7067) | Asian (n=4770) | P-value |
|---|---|---|---|---|---|
| Disease stage |
|
|
|
|
<0.0001a |
| Localised | 17 602 (51.6) | 3538 (44.3) | 3035 (44.3) | 2477 (52.9) | |
| Regional | 14 936 (43.8) | 3785 (47.4) | 3356 (48.9) | 1978 (42.3) | |
| Distant | 1581 (4.6) | 659 (8.3) | 465 (6.8) | 225 (4.8) | |
| Unknown |
982 |
233 |
211 |
90 |
|
| Age at diagnosis (years) |
|
|
|
|
0.0001b |
| Mean (median) | 35 (36) | 34.4 (35) | 34.5 (35) | 35 (36) | |
| <35 years | 12 421 (35.4) | 3499 (42.6) | 2930 (41.5) | 1718 (36.0) | <0.0001 |
| ⩾35 years |
22 680 (64.6) |
4716 (57.4) |
4137 (58.5) |
3052 (64.0) |
|
| Surgery |
|
|
|
|
<0.0001a |
| No primary surgery | 1030 (3.0) | 583 (7.2) | 477 (6.8) | 175 (3.7) | |
| SM | 11 835 (34.2) | 2929 (36.2) | 2584 (36.9) | 1775 (37.5) | |
| TM | 21 731 (62.8) | 4584 (56.6) | 3948 (56.3) | 2780 (58.8) | |
| Unknown |
505 |
119 |
58 |
40 |
|
| Tumour grade |
|
|
|
|
<0.0001a |
| I | 1816 (7.3) | 278 (4.6) | 336 (5.7) | 336 (8.8) | |
| II | 7905 (31.8) | 1521(24.9) | 1744 (29.5) | 1338 (35.0) | |
| III | 14 045 (56.4) | 4079 (66.8) | 3553 (60.1) | 2018 (52.7) | |
| IV | 1119 (4.5) | 225 (3.7) | 276 (4.7) | 135 (3.5) | |
| Unknown |
10216 |
2112 |
1158 |
943 |
|
| Histology |
|
|
|
|
<0.0001 |
| IDC | 26 973 (76.8) | 6227 (75.8) | 5441 (77.0) | 3793 (79.5) | |
| ILC | 1170 (3.3) | 194 (2.4) | 186 (2.6) | 97 (2.0) | |
| IDC and ILC | 1522 (4.3) | 231 (2.8) | 337 (4.8) | 194 (4.1) | |
| Other |
5436 (15.5) |
1563 (19.0) |
1103 (15.6) |
686 (14.4) |
|
| Oestrogen receptor status |
|
|
|
|
<0.0001a |
| Positive | 13 362 (62.0) | 2667 (49.9) | 3035 (57.8) | 2379 (67.8) | |
| Negative | 8010 (37.2) | 2636 (49.3) | 2185 (41.7) | 1115 (31.7) | |
| Borderline | 172 (0.8) | 42 (0.8) | 26 (0.5) | 17 (0.5) | |
| Unknown |
13 557 |
2870 |
1821 |
1259 |
|
| Progesterone receptor status |
|
|
|
|
<0.0001a |
| Positive | 11 995 (56.3) | 2280 (43.2) | 2606 (50.5) | 2180 (63.1) | |
| Negative | 9117 (42.8) | 2941 (55.8) | 2514 (48.7) | 1241 (35.9) | |
| Borderline | 198 (0.9) | 51 (1.0) | 41 (0.8) | 35 (1.0) | |
| Unknown |
13 791 |
2943 |
1906 |
1314 |
|
| Adjuvant radiation therapy |
|
|
|
|
<0.0001 |
| No | 21 357 (60.8) | 5105 (62.1) | 4206 (59.5) | 2722 (57.1) | |
| Yes |
13 744 (39.2) |
3110 (37.9) |
2861 (40.5) |
2048 (42.9) |
|
| Adjuvant radiation therapy after SM |
|
|
|
|
<0.0001 |
| No | 3576 (30.2) | 1107 (37.8) | 971 (37.6) | 532 (30.0) | |
| Yes |
8259 (69.8) |
1822 (62.2) |
1613 (62.4) |
1243 (70.0) |
|
| Adjuvant radiation therapy after TM |
|
|
|
|
<0.0001 |
| No | 16 318 (75.1) | 3331 (72.7) | 2721 (68.9) | 1984 (71.4) | |
| Yes | 5413 (24.9) | 1253 (27.3) | 1227 (31.1) | 796 (28.6) |
Abbreviations: IDC=invasive ductal cancer; ILC=invasive lobular cancer; SM=segmental mastectomy; TM=total mastectomy.
a
P-value calculated after excluded unknown category.
b
Kruskal–Wallis equality-of-populations rank test.