Table 4.
Occurrence of breast cancer in women aged 18 and over after benign breast disease in the English data set: time between admission for BBD and admission for breast cancer, number of women with breast cancer in the reference cohort, observed (Obs) and expected (Exp) number of women with cancer in the BBD cohort, ratio of rate of BBD cohort to that in the reference cohort and 95%confidence intervals for the RR
| Time intervalsa | Obs | Exp | Adjusted RRb (95% confidence interval) |
|---|---|---|---|
| All (17 338) | 1812 | 612.5 | 3.2 (3.0–3.3) |
| 1st mo. (1355) | 299 | 44.1 | 7.7 (6.8–8.7) |
| 1–11 mo. (4117) | 612 | 151.6 | 4.5 (4.1–4.9) |
| 1–4 y (10 615) | 811 | 369.1 | 2.3 (2.1–2.5) |
| 5–6 y (1251) | 90 | 47.8 | 2.0 (1.6–2.4) |
aNumber of women with breast cancer in the reference cohort in parentheses.
bAdjusted for age in 5-year age bands, time period in single calendar years and district of residence; comparing Obs/Exp in the BBD cohort (data in table) with Obs/Exp in the reference cohort (data not shown separately).