Table 3.

Risk of breast cancer by p16 expression with Ki-67 and COX-2

Staining categoryaNEventsExpected eventsSIR (95% CI)ePf
p16b0.99
 0%–10%158307.73.89 (2.72–5.56)
 11+%75174.43.91 (2.43–6.28)
p16/Ki-67c0.92
 0%–10%/2+3231.61.86 (0.60–5.78)
 0%–10%/<284144.43.20 (1.90–5.41)
 11+%/2+1951.14.47 (1.86–10.7)
 11+%/<23762.32.66 (1.20–5.93)
p16/COX-2d0.03
 0%–10%/0 or 1+7383.92.08 (1.04–4.15)
 0%–10%/2+ or 3+601234.01 (2.28–7.07)
 11+%/0 or 1+3742.21.78 (0.67–4.74)
 11+%/2+ or 3+3291.85.03 (2.62–9.66)
  • ap16 results based on 233 subjects with p16 results; p16/Ki-67 combinations based 172 subjects with both p16 and Ki-67 results; p16/COX-2 combinations based on 202 subjects with both p16 and COX-2 results.

  • bp16 staining is dichotomized as percentage of cells stained, 0% to 10% versus 11+%.

  • cKi-67 staining is dichotomized as percentage of cells stained, 0 or 1 versus 2 or higher (10).

  • dCOX-2 staining is dichotomized by general staining intensity, 0 or 1+ versus 2+ or 3+ (11).

  • eSIR and corresponding 95% CIs, comparing the observed number of breast cancer events to those expected on the basis of incidence rates from Iowa SEER data. Analyses account for the effects of age and calendar period.

  • fTest for heterogeneity of the SIR across staining levels.