Table 2.

ORs (95% CI) of developing subsequent breast cancer according to tertiles of mean percentage of p27+, ER+, and Ki67+ in normal breast tissue in the NHS and the NHSII

Model 1aModel 2b
CaseControlOR (95% CI)OR (95% CI)
Percentage of p27+ cells
 <8.0 %25751.0 (Ref)1.0 (Ref)
 8.0%–25.4%21780.73 (0.37–1.46)0.86 (0.42–1.76)
 ≥25.5%23780.84 (0.43–1.63)0.89 (0.45–1.75)
Per 1% increase1.00 (0.98–1.02)1.00 (0.99–1.02)
Ptrend0.990.97
Percentage of ER+ cells
 <3.0%24721.0 (Ref)1.0 (Ref)
 3.0%–9.9%22710.98 (0.49–1.94)0.90 (0.45–1.80)
 ≥10.0%19760.86 (0.42–1.77)0.70 (0.33–1.50)
Per 1% increase1.00 (0.98–1.03)1.00 (0.97–1.02)
Ptrend0.860.84
Percentage of Ki67+ cells
 <0.28%13641.0 (Ref)1.0 (Ref)
 0.28%–2.0%18601.66 (0.72–3.85)1.63 (0.70–3.80)
 ≥2.0%21551.94 (0.85–4.44)1.92 (0.83–4.43)
Per 1% increase1.05 (0.98–1.13)1.05 (0.98–1.13)
Ptrend0.150.14
Percentage of p27+ER+ cells
 <1.5%22721.0 (Ref)1.0 (Ref)
 1.5%–5.4%26681.33 (0.67–2.61)1.23 (0.62–2.45)
 ≥5.5%17790.77 (0.37–1.60)0.69 (0.33–1.46)
Per 1% increase1.00 (0.96–1.04)1.00 (0.96–1.04)
Ptrend0.910.97
Percentage of p27+Ki67+ cells
 <0.16%22821.0 (Ref)1.0 (Ref)
 0.16%–1.4%11401.11 (0.47–2.61)1.24 (0.52–2.96)
 ≥1.5%19571.29 (0.61–2.71)1.36 (0.64–2.90)
Per 1% increase1.03 (0.86–1.22)1.05 (0.88–1.25)
Ptrend0.760.62
  • aModel 1 (matching factors only): age at diagnosis (continuous, years), calendar year of biopsy (<1970, 1970–1980, 1980+), time since biopsy (continuous, years).

  • bModel 2: Model 1 + type of benign lesion (nonproliferative, proliferative without atypia, proliferative with atypia).