Table 2.
Patient numbers, person-years of follow-up, standardized incidence ratios, and cumulative risks of breast cancer at age 40, by major risk categories
| Subgroup | No. patients | PY | SIR | No. BC | BC Exp. | BC risk @ age 40 (%) | 95% CI |
|---|---|---|---|---|---|---|---|
| All patients | 2,492 | 31,755 | 9.1 | 29 | 3.20 | 4.5 | 2.8–7.2 |
| RT Group* | |||||||
| No RT | 1,229 | 13,560 | 2.2 | 2 | 0.92 | 0.3 | 0.0–2.3 |
| Abdominal RT only | 894 | 13,185 | 6.0 | 10 | 1.67 | 3.1 | 1.3–7.1 |
| Chest RT | 369 | 5,010 | 27.6 | 17 | 0.62 | 14.8 | 8.7–24.5 |
| Chest dose* | |||||||
| 0 Gy | 2,122.9 | 26,746 | 4.6 | 12 | 2.59 | 2.3 | 1.0–5.1 |
| 1–12 Gy | 246.9 | 2,857 | 46.8 | 9 | 0.19 | 14.4 | 7.6–30.1 |
| >12 Gy | 122.2 | 2,153 | 18.9 | 8 | 0.42 | 14.2 | 7.1–29.3 |
| Age at WT (years) | |||||||
| 0–4 | 1,856 | 22,326 | 6.0 | 11 | 1.84 | 3.1 | 1.5–6.3 |
| 5–9 | 546 | 7,967 | 9.2 | 9 | 0.98 | 4.4 | 2.0–9.1 |
| 10–19 | 90 | 1,463 | 23.6 | 9 | 0.38 | 13.5 | 5.6–30.6 |
| Doxorubicin | |||||||
| No | 1,518 | 19,742 | 4.8 | 11 | 2.29 | 2.6 | 1.2–5.4 |
| Yes | 974 | 12,013 | 19.7 | 18 | 0.91 | 9.4 | 4.9–17.4 |
| Current age (years) | |||||||
| 15–24 | 2,492 | 19,979 | 21.3 | 3 | 0.14 | NA | NA |
| 25–29 | 1,491 | 6,086 | 6.4 | 3 | 0.47 | ||
| 30–35 | 942 | 3,527 | 11.1 | 10 | 0.90 | ||
| 35–39 | 477 | 1,580 | 9.6 | 9 | 0.94 | ||
| 40+ | 184 | 582 | 5.3 | 4 | 0.75 |