Table 5.

Recurrence-Free Survival with Cox Multivariate Analysis According to β-Arrestin-1 Expression and Treatment Interaction for Patients in Cohort II

ERα positive (n = 384)⁎	Multivariate HR (95% CI)	P
β-arrestin-1 stroma		<0.001
Negative or high	1.00
Low or moderate	0.27 (0.13−0.55)†
Treatment		0.001
Control	1.00
Tamoxifen	0.12 (0.03−0.44)‡
Interaction variable§		0.017
Value	5.31 (1.34–20.96)

CI, Confidence interval; HR, hazard ratio; NHG, Nottingham histologic grade.

^⁎Other factors included in the multivariate analysis: age (continuous), tumor grade (NHG I+II versus III), proliferation (Ki67 0–1, 2–10, 11–25, 26–50, 51–100%), and nodal status (negative versus positive).

^†Stromal β-arrestin-1 hazard ratio for the control group.

^‡Treatment hazard ratio for the stromal β-arrestin-1 subgroup of negative or high expression.

^§Interaction variable states whether there is a difference in the treatment response in relation to stromal β-arrestin-1 status.