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Table 1 Baseline characteristics by diagnosis period

From: Impact of the COVID-19 pandemic on diagnosis, stage, and initial treatment of breast cancer in the Netherlands: a population-based study

  Weeks 2–8 Weeks 9–11 Weeks 12–13 Weeks 14–17
2018/2019a 2020 p 2018/2019a 2020 p 2018/2019a 2020 p 2018/2019a 2020 p
Patients 2547.5 2692   1074.5 995   737.5 436   1402 646  
Age             
 < 40 129.5 (5.1) 142 (5.3) 0.02 51 (4.8) 44 (4.4) 0.55 36.5 (5.0) 19 (4.4) 0.42 54 (3.9) 64 (9.9) < 0.01
 40–49 389.5 (15.3) 372 (13.8) 158.5 (14.8) 128 (12.9) 104.5 (14.2) 62 (14.2) 204.5 (14.6) 111 (17.2)
 50–64 912.5 (35.8) 898 (33.4) 387.5 (36.1) 368 (37.0) 266.5 (36.1) 175 (40.1) 524.5 (37.4) 200 (31.0)
 65–74 674 (26.5) 771 (28.6) 284.5 (26.5) 282 (28.3) 206.5 (28.0) 121 (27.8) 358 (25.5) 118 (18.3)
 > 74 442 (17.4) 509 (18.9) 193 (18.0) 173 (17.4) 123.5 (16.8) 59 (13.5) 261 (18.6) 153 (23.7)
SES             
 High 782.5 (30.7) 788 (29.3) < 0.01 295.5 (27.5) 316 (31.8) 0.04 211.5 (28.7) 133 (30.5) 0.47 410.5 (29.3) 206 (31.9) 0.28
 Medium 992.5 (39.0) 1169 (43.4) 421 (39.2) 379 (38.1) 282.5 (38.3) 153 (35.1) 569.5 (40.6) 242 (37.5)
 Low 763.5 (30.0) 719 (26.7) 355 (33.0) 298 (30.0) 239.5 (32.5) 148 (33.9) 413.5 (29.5) 193 (29.9)
 Unknown 9 (0.4) 16 (0.6) 3 (0.3) 2 (0.2) 4 (0.5) 2 (0.5) 8.5 (0.6) 5 (0.8)
Morphology             
 DCIS 309 (12.1) 352 (13.1) 0.44 119.5 (11.1) 125 (12.6) 0.33 79.5 (10.8) 65 (14.9) 0.03 178 (12.7) 42 (6.5) 0.00
 Invasive ductal 1761.5 ( 69.2) 1828 (67.9) 756 (70.4) 671 (67.4) 504.5 (68.4) 294 (67.4) 951 (67.8) 480 (74.3)
 Invasive lobular 342.5 (13.4) 380 (14.1) 135 (12.6) 141 (14.2) 122 (16.5) 55 (12.6) 198 (14.1) 92 (14.2)
 Other 134.5 (5.3) 132 (4.9) 64 (6.0) 58 (5.8) 31.5 (4.3) 22 (5.1) 75 (5.4) 32 (5.0)
Stage             
 DCIS 309 (12.2) 352 (13.2) 0.25 119.5 (11.1) 125 (12.6) 0.69 79.5 (10.8) 65 (15.0) 0.09 178 (12.7) 42 (6.6) < 0.01
 Stage I 1044.5 (41.1) 1075 (40.4) 446 (41.6) 418 (42.2) 306 (41.6) 167 (38.6) 559.5 (40.0) 212 (33.1)
 Stage II 828.5 (32.6) 891 (33.5) 358 (33.4) 316 (31.9) 247 (33.6) 142 (32.8) 473.5 (33.8) 269 (42.0)
 Stage III 233.5 (9.2) 211 (7.9) 97 (9.0) 82 (8.3) 72 (9.8) 35 (8.1) 122 (8.7) 64 (10.0)
 Stage IV 128 (5.0) 134 (5.0) 52 (4.9) 49 (5.0) 31 (4.2) 24 (5.5) 66.5 (4.8) 54 (8.4)
Subtype             
 HR+/HER2+ 210 (8.2) 171 (6.4) 0.01 74.5 (6.9) 64 (6.4) 0.88 48.5 (6.6) 30 (6.9) 0.59 111.5 (8.0) 62 (9.6) 0.12
 HR+/HER2– 1678 (65.9) 1743 (64.8) 717 (66.7) 657 (66.0) 510 (69.2) 286 (65.6) 921.5 (65.7) 428 (66.3)
 HR−/HER2+ 83 (3.3) 65 (2.4) 41.5 (3.9) 33 (3.3) 30 (4.1) 11 (2.5) 42 (3.0) 30 (4.6)
 HR−/HER2− 249 (9.8) 275 (10.2) 112 (10.4) 98 (9.9) 64.5 (8.8) 35 (8.0) 137.5 (9.8) 76 (11.8)
 Unknown 327.5 (12.9) 438 (16.3) 129.5 (12.1) 143 (14.4) 84.5 (11.5) 74 (17.0) 189.5 (13.5) 50 (7.7)
Region             
 North 257.5 (10.1) 254 (9.4) 0.02 111.5 (10.4) 99 (10.0) 0.74 74 (10.0) 46 (10.6) 0.17 135 (9.6) 71 (11.0) 0.86
 Middle East 230.5 (9.1) 257 (9.6) 98.5 (9.2) 97 (9.8) 71.5 (9.7) 55 (12.6) 123.5 (8.8) 59 (9.1)
 Middle 488 (19.2) 589 (21.9) 214 (19.9) 208 (20.9) 139 (18.9) 94 (21.6) 297.5 (21.2) 132 (20.4)
 West 1010.5 (39.7) 991 (36.8) 406 (37.8) 384 (38.6) 304.5 (41.3) 165 (37.8) 538 (38.4) 246 (38.1)
 South 560.5 (22.0) 600 (22.3) 244.5 (22.8) 207 (20.8) 148.5 (20.1) 76 (17.4) 308 (22.0) 138 (21.4)
Screened             
 Yes 810 (31.8) 837 (31.1) 0.87 354.5 (33.0) 342 (34.4) 0.43 256.5 (34.8) 172 (39.5) 0.12 455.5 (32.5) 12 (1.9) 0.00
 No 727.5 (28.6) 762 (28.3) 299 (27.8) 275 (27.6) 201.5 (27.3) 107 (24.5) 403.5 (28.8) 282 (43.7)
 Not eligible 961 (37.7) 1023 (38.0) 402.5 (37.5) 345 (34.7) 264.5 (35.9) 140 (32.1) 519.5 (37.1) 328 (50.8)
 Unknown 49 (1.9) 70 (2.6) 18.5 (1.7) 33 (3.3) 15 (2.0) 17 (3.9) 23.5 (1.7) 24 (3.7)
  1. Data are reported as N (%) of patients diagnosed in weeks 2–17 of 2018/2019 or 2020
  2. The p value was calculated on known values only, using the chi-square test to compare patients diagnosed in weeks 2–8, 9–11, 12–13, or 14–17 of 2020 with those diagnosed in the same period from the average for the years 2018 and 2019
  3. DCIS, ductal carcinoma in situ; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; SES, socioeconomic status
  4. aThe average was taken over 2018 and 2019