Table 1.
Demographic and clinical characteristics of study population (N = 3,223)
| Characteristics | Overall1 | PBC | SPC1 | SPBC | SPNBC |
|---|---|---|---|---|---|
| N = 3,223 | N = 2,504 | N = 719 | N = 323 | N = 396 | |
| Race/Ethnicity | |||||
| White | 755 (23.4) | 563 (22.5) | 192 (26.7) | 79 (24.5) | 113 (28.5) |
| African American | 600 (18.6) | 466 (18.6) | 134 (18.6) | 60 (18.6) | 74 (18.7) |
| Native Hawaiian | 268 (8.3) | 197 (7.9) | 71 (9.9) | 38 (11.8) | 33 (8.3) |
| Japanese American | 992 (30.8) | 786 (31.4) | 206 (28.7) | 102 (31.6) | 104 (26.3) |
| Latino | 608 (18.9) | 492 (19.6) | 116 (16.1) | 44 (13.6) | 72 (18.2) |
| Age at cohort entry, mean (sd) | 59.4 (8.2) | 59.3 (8.3) | 59.8 (8.0) | 58.8 (8.0) | 60.7 (7.8) |
| Age at 1st BC diagnosis | |||||
| Mean (sd) | 67.7 (9.0) | 68.1 (9.1) | 66.5 (8.7) | 65.5 (9.1) | 67.3 (8.2) |
| 45-60 | 690 (21.4) | 513 (20.5) | 177 (24.6) | 100 (31.0) | 77 (19.4) |
| 60-70 | 1184 (36.7) | 910 (36.3) | 274 (38.1) | 110 (34.1) | 164 (41.4) |
| 70-80 | 1077 (33.4) | 842 (33.6) | 235 (32.7) | 100 (31.0) | 135 (34.1) |
| 80+ | 272 (8.4) | 239 (9.5) | 33 (4.6) | 13 (4.0) | 20 (5.1) |
| First-degree family history of BC | |||||
| Negative | 2571 (79.8) | 2023 (80.8) | 548 (76.2) | 240 (74.3) | 308 (77.8) |
| Positive | 505 (15.7) | 366 (14.6) | 139 (19.3) | 63 (19.5) | 76 (19.2) |
| Missing | 147 (4.6) | 115 (4.6) | 32 (4.5) | 20 (6.2) | 12 (3.0) |
| Tumor stage of 1st BC | |||||
| Localized | 2318 (71.9) | 1784 (71.2) | 534 (74.3) | 242 (74.9) | 292 (73.7) |
| Regional | 786 (24.4) | 615 (24.6) | 171 (23.8) | 74 (22.9) | 97 (24.5) |
| Distant | 55 (1.7) | 47 (1.9) | 8 (1.1) | 5 (1.5) | 3 (0.8) |
| Missing | 64 (2.0) | 58 (2.3) | 6 (0.8) | 2 (0.6) | 4 (1.0) |
| Estrogen receptor (ER) status of 1st BC | |||||
| Negative | 538 (16.7) | 420 (16.8) | 118 (16.4) | 55 (17.0) | 63 (15.9) |
| Positive | 2333 (72.4) | 1831 (73.1) | 502 (69.8) | 222 (68.7) | 280 (70.7) |
| Missing | 352 (10.9) | 253 (10.1) | 99 (13.8) | 46 (14.3) | 53 (13.4) |
| Progesterone receptor (PR) status of 1st BC | |||||
| Negative | 801 (24.9) | 621 (24.8) | 180 (25.0) | 77 (23.8) | 103 (26.0) |
| Positive | 1935 (60.0) | 1526 (60.9) | 409 (56.9) | 186 (57.6) | 223 (56.3) |
| Missing | 487 (15.1) | 357 (14.3) | 130 (18.1) | 60 (18.6) | 70 (17.7) |
| Radiation Treatment of 1st BC2 | |||||
| Not administered | 1523 (47.3) | 1185 (47.3) | 338 (47.0) | 163 (50.5) | 175 (44.2) |
| Administered | 1655 (51.3) | 1281 (51.2) | 374 (52.0) | 156 (48.3) | 218 (55.1) |
| Missing | 45 (1.4) | 38 (1.5) | 7 (1.0) | 4 (1.2) | 3 (0.8) |
| Chemotherapy of 1st BC2 | |||||
| Not administered | 2249 (69.8) | 1751 (69.9) | 498 (69.3) | 218 (67.5) | 280 (70.7) |
| Administered | 899 (27.9) | 692 (27.6) | 207 (28.8) | 100 (31.0) | 107 (27.0) |
| Missing | 75 (2.3) | 61 (2.4) | 14 (1.9) | 5 (1.5) | 9 (2.3) |
| Hormonal Therapy of 1st BC2 | |||||
| Not administered | 1675 (52.0) | 1291 (51.6) | 384 (53.4) | 181 (56.0) | 203 (51.3) |
| Administered | 1452 (45.1) | 1138 (45.4) | 314 (43.7) | 133 (41.2) | 181 (45.7) |
| Missing | 96 (3.0) | 75 (3.0) | 21 (2.9) | 9 (2.8) | 12 (3.0) |
Abbreviation: BC, breast cancer; PBC, primary breast cancer; SPC, second primary cancer; SPBC, second primary breast cancer; SPNBC, second primary non-breast cancer.
1
The first primary breast cancer was diagnosed between 1993 and 2016 and the second primary cancer was diagnosed between 1994-2017.
2
First-course treatment from SEER cancer registry.