Table 2 SIRs for contralateral breast cancer among 1-year survivors of a first primary breast cancer in 12 SEER registries, 1992–2016
First breast cancer characteristic | No. of CBCs (%) | SIR (95% CI) |
|---|---|---|
Overall | 12,986 (100.0) | 2.21 (2.17 to 2.25) |
Age at diagnosis, years | ||
< 40 | 1002 (7.7) | 6.41 (6.02 to 6.82) |
40 to < 50 | 2691 (20.7) | 2.79 (2.69 to 2.90) |
50 to < 60 | 3452 (26.6) | 2.07 (2.00 to 2.14) |
60 to < 70 | 3292 (25.4) | 1.91 (1.85 to 1.98) |
≥ 70 | 2549 (19.6) | 1.87 (1.80 to 1.94) |
Time since diagnosis | ||
< 5 years | 4620 (35.6) | 2.03 (1.97 to 2.09) |
≥ 5 years | 8366 (64.4) | 2.32 (2.27 to 2.37) |
Stage at diagnosis | ||
I | 6899 (53.1) | 2.08 (2.03 to 2.13) |
II | 4364 (33.6) | 2.21 (2.14 to 2.28) |
III | 1723 (13.3) | 2.97 (2.83 to 3.11) |
Histology | ||
Ductal | 9340 (71.9) | 2.17 (2.13 to 2.21) |
Lobular | 1037 (8.0) | 2.06 (1.94 to 2.19) |
Mixed | 1126 (8.7) | 2.49 (2.35 to 2.64) |
Other | 1483 (11.4) | 2.44 (2.32 to 2.57) |
ER status | ||
Positive | 8372 (64.5) | 1.98 (1.94 to 2.02) |
Negative | 3024 (23.3) | 3.05 (2.94 to 3.16) |
Initial treatment | ||
Radiation therapy | ||
Yes | 7180 (55.3) | 2.25 (2.20 to 2.30) |
No/unknown | 5806 (44.7) | 2.17 (2.11 to 2.23) |
Chemotherapy | ||
Yes | 5086 (39.2) | 2.49 (2.42 to 2.56) |
No/unknown | 7900 (60.8) | 2.06 (2.01 to 2.11) |
Hormone therapy | ||
Yes | 4442 (34.2) | 1.88 (1.83 to 1.94) |
No/unknown | 8544 (65.8) | 2.43 (2.38 to 2.48) |
HER2 statusa | ||
Positive | 93 (11.8) | 1.45 (1.17 to 1.78) |
Negative | 646 (82.2) | 1.57 (1.45 to 1.70) |
Breast cancer subtypea,b | ||
HR+/HER2+ | 66 (8.4) | 1.47 (1.14 to 1.87) |
HR+/HER2− | 534 (67.9) | 1.47 (1.35 to 1.60) |
HR−/HER2+ | 27 (3.4) | 1.42 (0.94 to 2.07) |
HR−/HER2− (triple negative) | 111 (14.1) | 2.43 (2.00 to 2.93) |