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Table 2 Standardized incidence ratio (SIR) of a second breast event (contralateral in situ or ipsilateral or contralateral invasive breast cancer) after diagnosis of first in situ breast cancer and its 95 % CI, by type of second breast event and family history

From: The impact of in situ breast cancer and family history on risk of subsequent breast cancer events and mortality - a population-based study from Sweden

  All No family history Family history Incidence rate ratiod
  Number SIR Number SIR Number SIR  
   (95 % CI)   (95 % CI)   (95 % CI) (95 % CI)
Second breast cancera 886 5.1 (4.8–5.4) 781 5.0 (4.6 − 5.3) 105 6.3 (5.1–7.6) 1.2 (1.0–1.4)
Second contralateral in situ a 118 16.0 (13.2–19.1) 104 15.8 (12.9–19.2) 14 17.4 (9.5– 29.3) 1.1 (0.6–1.9)
Second invasiveb 768 4.6 (4.2–4.9) 677 4.4 (4.1–4.7) 91 5.6 (4.5–6.9) 1.2 (1.0–1.5)
Second ipsilateral invasivec 376 4.3 (3.8–4.7) 334 4.2 (3.8–4.7) 42 5.0 (3.6–6.7) 1.00 (0.7– 1.4)
Second contralateral invasivec 303 3.4 (3.1–3.8) 262 3.3 (2.9–3.7) 41 4.8 (3.5–6.5) 1.5 (1.0–2.0)
  1. aBackground rate of in situ breast cancer was divided by 2. bIincludes ipsilateral, contralateral and missing side. cBackground rate of invasive breast cancer was divided by 2. dReference group is No family history. Incidence rate ratio has been adjusted for age and year of first diagnosis of in situ cancer and time since first diagnosis