Table 4.

ORs (95% CI) of developing subsequent breast cancer according to cross-classified groups of Ki67 and p27, Ki67 and ER, p27 and ER in normal breast tissue among premenopausal women in the NHS and the NHSII

Tissue expressionCaseControlOR (95% CI)
Ki67 and p27 (cross-classified)
 Low Ki67 (<1.15%)Low p27 (<16.6 %)4391.0 (Ref)
High p27 (16.6+ %)6351.99 (0.49–8.0)
 High Ki67 (1.15+%)Low p27 (<16.6 %)14305.08 (1.43–18.1)
High p27 (16.6+ %)11313.5 (0.98–12.5)
Ki67 and ER (cross-classified)
 Low Ki67 (<1.15%)Low ER (<5.3 %)6431.0 (Ref)
High ER (5.3+ %)3261.08 (0.23–5.01)
 High Ki67 (1.15+%)Low ER (<5.3 %)20334.68 (1.63–13.5)
High ER (5.3+ %)3250.90 (0.20–4.08)
p27 and ER (cross-classified)
 Low ER (<5.3%)Low p27 (<16.6 %)18611.0 (Ref)
High p27 (16.6+ %)18431.51 (0.69–3.31)
 High ER (5.3+%)Low p27 (<16.6 %)6181.27 (0.43–3.79)
High p27 (16.6+ %)4400.39 (0.12–1.25)

NOTE: The fraction of p27+, ER+, and Ki67+ in normal breast tissue were dichotomized around the median (above vs. below median percentage of stain-positive cells). OR and 95% CIs were estimated using matching factors only model: age at diagnosis (continuous, years), calendar year of biopsy (<1970, 1970–1980, 1980+), time since biopsy (continuous, years). Numbers in bold and italic are statistically significant.