Table 1 Standardised incidence ratios (SIRs) of breast cancer by age
| Â | Â | Age at baseline | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Variables | Total | 25− | 30− | 35− | 40− | 45− | 50− | 55− | 60− | 65− | 70− | 75− | 80− | 85+ |
Frequency | 1492 | 171 | 152 | 176 | 214 | 167 | 144 | 108 | 86 | 63 | 76 | 56 | 44 | 35 |
Person-years | 9109 | 738 | 794 | 1032 | 1215 | 1183 | 1003 | 737 | 579 | 467 | 438 | 364 | 291 | 268 |
New breast cancers Observed (N) | 65 | 2 | 4 | 5 | 6 | 6 | 10 | 7 | 5 | 6 | 7 | 4 | 1 | 2 |
New breast cancers expected (N) | 16.49 | 0.05 | 0.16 | 0.53 | 1.23 | 2.06 | 2.17 | 1.85 | 1.64 | 1.60 | 1.61 | 1.45 | 1.15 | 0.99 |
Rate per 105 observed | 713.6 | 271.0 | 503.8 | 484.5 | 493.8 | 507.2 | 997.0 | 949.8 | 863.6 | 1284.8 | 1598.2 | 1098.9 | 343.6 | 746.3 |
Rate per 105 expected | 181.0 | 6.8 | 20.8 | 51.5 | 101.4 | 173.9 | 216.6 | 250.8 | 284 | 342.7 | 366.9 | 397.6 | 393.7 | 369.1 |
SIR | 3.9 | 40.1 | 30.3 | 9.4 | 5 | 2.9 | 4.1 | 3.8 | 3.1 | 3.8 | 5 | 2.8 | 0.9 | 2.1 |
95% CI | 3.1–5.0 | 11.0–146 | 7.8–51 | 4.3–23.4 | 2.3–10.9 | 1.3–6.2 | 2.5–8.4 | 1.9–8.0 | 1.3–7.3 | 1.7–8.2 | 2.1–9.0 | 1.1–7.3 | 0.2–5.1 | 0.6–7.3 |
P-value | <0.0001 | 0.02 | 0.002 | 0.002 | 0.007 | 0.05 | 0.0008 | 0.009 | 0.05 | 0.02 | 0.006 | 0.10 | 0.92 | 0.41 |
