Table 1. Characteristics of cases by study.
| SEARCH | NBCS | UBCBCS | MCCS | BCCA | Total | |
|---|---|---|---|---|---|---|
| No. of patients | 3420 | 1926 | 976 | 850 | 4040 | 11 212 |
| Mean age (years, range) | 52 (23–69) | 54 (18–70) | 48 (22–90) | 60 (41–79) | 59 (23–95) | 55 (18–95) |
| Mean follow-up (years, range) | 7.3 (0.5–15.9) | 5.2 (0–12.6) | 9.7 (0–39.4) | 7.2 (0–16.2) | 10.9 (0–18.5) | 8.4 (0–39.4) |
| Number of deaths (%) | 469 (14) | 416 (22) | 492 (50) | 133 (16) | 1136 (28) | 2646 (24) |
| Annual mortality (%) | 2.3 | 4.2 | 5.8 | 1.7 | 2.7 | 3.0 |
| Tumour size (n (%)) | ||||||
| <2 cm | 1272 (57) | 1023 (53) | 114 (12) | 543 (66) | 1594 (40) | 5133 (52) |
| 2–4.9 cm | 872 (39) | 853 (44) | 569 (62) | 262 (32) | 2108 (53) | 4092 (42) |
| ⩾5 cm | 93 (4) | 42 (2) | 238 (26) | 23 (3) | 301 (8) | 568 (6) |
| Grade (n (%)) | ||||||
| 1 | 624 (22) | 363 (19) | 68 (9) | 171 (22) | 211 (5) | 1436 (14) |
| 2 | 1350 (47) | 645 (34) | 234 (32) | 348 (44) | 1578 (41) | 4108 (41) |
| 3 | 884 (31) | 907 (47) | 425 (59) | 265 (34) | 2067 (54) | 4522 (45) |
| Nodal status (n (%)) | ||||||
| Negative | 1346 (62) | 1218 (64) | 238 (30) | 521 (66) | 2156 (55) | 5397 (57) |
| Positive | 834 (38) | 695 (36) | 562 (70) | 228 (30) | 1741 (45) | 4031 (43) |
| ER status (n (%)) | ||||||
| Negative | 657 (20) | 536 (30) | 491 (55) | 129 (28) | 1224 (31) | 3050 (29) |
| Positive | 2681 (80) | 1253 (70) | 409 (45) | 333 (72) | 2785 (69) | 7542 (71) |
| PR status (n (%)) | ||||||
| Negative | 708 (30) | 772 (44) | 503 (60) | 222 (48) | 1758 (49) | 3692 (44) |
| Positive | 1621 (70) | 993 (56) | 338 (40) | 237 (51) | 1843 (51) | 5110 (56) |
| HER2 status (n (%)) | ||||||
| Negative | 1329 (89) | 1341 (92) | 637 (71) | 407 (88) | 3355 (87) | 7006 (86) |
| Positive | 172 (11) | 116 (8) | 256 (29) | 54 (12) | 506 (13) | 1094 (14) |
| BCL2 status (n (%)) | ||||||
| Negative | 488 (24) | 270 (27) | 258 (35) | 198 (43) | 971 (26) | 2132 (27) |
| Positive | 1509 (76) | 714 (73) | 471 (65) | 265 (57) | 2743 (74) | 5671 (73) |
Abbreviations: BCCA=British Columbia Cancer Agency Case Series; BCL2=B-cell lymphoma 2; ER=oestrogen receptor; HER2=human epidermal growth factor receptor 2; MCCS=Melbourne Collaborative Cohort Study; NBCS=Nottingham Breast Cancer Series; PR=progesterone receptor; SEARCH=Study of Epidemiology and Risk Factors in Cancer Heredity; UBCBCS=University of British Columbia Breast Cancer Series.