Table 2.
Effect estimates for breast cancer mortality in the Copenhagen mammography screening programme
| Study group | 50-54 | 55-59 | 60-64 | 65-69 | 70-74 | 75-79 | All age groups |
|---|---|---|---|---|---|---|---|
| No of breast cancer deaths | 9 | 34 | 43 | 53 | 56 | 28 | 223 |
| Person years | 64 144 | 92 734 | 83 510 | 87 408 | 77 427 | 25 600 | 430 823 |
| Breast cancer mortality per 100 000 person years | 14 | 37 | 51 | 61 | 72 | 109 | 52 |
| National control group* | |||||||
| No of breast cancer deaths | 89 | 434 | 516 | 535 | 545 | 214 | 2333 |
| Person years | 767 111 | 1 067 778 | 906 943 | 826 254 | 635 385 | 192 946 | 4 396 417 |
| Breast cancer mortality per 100 000 person years | 12 | 41 | 57 | 65 | 86 | 111 | 53 |
| Historical control group | |||||||
| No of breast cancer deaths | 22 | 45 | 82 | 104 | 128 | 57 | 438 |
| Person years | 57 669 | 113 143 | 139 065 | 155 697 | 128 454 | 40 196 | 634 224 |
| Breast cancer mortality per 100 000 person years | 38 | 40 | 59 | 67 | 100 | 142 | 69 |
| Historical national control group† | |||||||
| No of breast cancer deaths | 104 | 443 | 485 | 491 | 418 | 182 | 2123 |
| Person years | 577 528 | 931 245 | 916 923 | 838 476 | 608 008 | 182 824 | 4 055 004 |
| Breast cancer mortality per 100 000 person years | 18 | 48 | 53 | 59 | 69 | 100 | 52 |
| Relative risk estimates (95% confidence interval) | |||||||
| Study group compared with national control group* | 1.21 (0.61 to 2.40) | 0.90 (0.64 to 1.28) | 0.91 (0.66 to 1.24) | 0.94 (0.71 to 1.24) | 0.84 (0.64 to 1.11) | 0.99 (0.67 to 1.46) | 0.91 (0.80 to 1.05) |
| Historical control group compared with historical national control group† | 2.12 (1.34-3.36) | 0.84 (0.62 to 1.14) | 1.11 (0.88 to 1.41) | 1.14 (0.92 to 1.41) | 1.45 (1.19 to 1.77) | 1.42 (1.06 to 1.92) | 1.22 (1.10 to 1.35) |
| Study group compared with historical control group | 0.37 (0.17-0.80) | 0.92 (0.59 to 1.44) | 0.87 (0.60 to 1.26) | 0.91 (0.65 to 1.26) | 0.73 (0.53 to 0.99) | 0.77 (0.49 to 1.21) | 0.80 (0.68 to 0.94) |
| National control group* compared with historical national control group† | 0.64 (0.49-0.86) | 0.85 (0.75 to 0.98) | 1.08 (0.95 to 1.22) | 1.11 (0.98 to 1.25) | 1.25 (1.10 to 1.42) | 1.11 (0.91 to 1.36) | 1.05 (0.99 to 1.11) |
| Combined effect of invitation to screening and interaction between region and period | 0.57 (0.25-1.30) | 1.08 (0.68 to 1.72) | 0.81 (0.55 to 1.20) | 0.82 (0.58 to 1.17) | 0.58 (0.41 to 0.82) | 0.69 (0.42 to 1.13) | 0.75 (0.63 to 0.89) |
*
National control group (Denmark except Copenhagen, Fyn, and Frederiksberg).
†
Historical national control group (Denmark except Copenhagen, Fyn, and Frederiksberg).