Table 2.
Occurrence of breast cancer in women aged 18 and over after benign breast disease in the ORLS area: time between admission for BBD and admission for breast cancer, number of women with breast cancer in the reference cohort, observed (Obs) number of women with cancer in the BBD cohort, expected (Exp) number of women with cancer in the BBD cohort, ratio of rate in BBD cohort to that in the reference cohorta and 95% confidence intervals for the RR
| Time intervals | Obs | Exp | Adjusted RRb (95% confidence interval) |
|---|---|---|---|
| All (4442) | 850 | 400.3 | 2.3 (2.2–2.5) |
| 1st month (96) | 113 | 12.5 | 18.4 (13.9–24.5) |
| 1–11 months (308) | 70 | 18.5 | 4.4 (3.4–5.7) |
| 1–4 years (1172) | 173 | 78.0 | 2.4 (2.0–2.8) |
| 5–9 years (1102) | 180 | 96.2 | 2.0 (1.7–2.4) |
| 10–19 years (1303) | 241 | 144.9 | 1.8 (1.6–2.0) |
| 20+ years (461) | 73 | 50.2 | 1.5 (1.2–2.0) |
aConditions used in the reference cohort with ICD9 code for diagnosis (with equivalent codes used for other coding editions): varicose veins (454), haemorrhoids (455), upper respiratory tract infections (460), deflected septum, nasal polyp (470–471), impacted tooth and disorders of teeth (520–521), inguinal hernia (550), in-growing toenail and other diseases of nail (703), sebaceous cyst (706.2), internal derangement of knee (717), bunion (727.1), squint (378), otitis externa and otitis media (380–382), selected fractures (810–816, 823–826), dislocations sprains and strains (830–839, 840–848) and superficial injury and contusion (910–919, 920–924).
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).