Table 2.

Results of Proportional Hazards Multivariate Models for DFS and OS Using ErbB-2 Score as a Dichotomous Variable (dichotomized at ≥ 50%) and Phosphorylated ErbB-2 (P-ErbB-2, PN2A) Score Modeled as a Dichotomous Variable (0 v > 0)

Parameter	DFS									OS
		RR	95% CI	df	χ2	P	RR	95% CI	df	χ2	P
RR
ErbB-2	1.30	0.91 to 1.85				1.54	1.09 to 2.31
P-ErbB-2	1.39	0.88 to 2.18				1.56	0.97 to 2.52
Medium dose
ErbB-2 × CAF	1.26	0.73 to 1.99				1.18	0.69 to 2.03
P-ErbB-2 × CAF	1.11	0.60 to 2.08				0.83	0.42 to 1.63
High dose
ErbB-2 × CAF	0.56	0.33 to 0.96				0.34	0.22 to 0.71
P-ErbB-2 × CAF	0.72	0.37 to 1.42				0.55	0.25 to 1.16
Likelihood-ratio tests
ErbB-2			1	2.13	.14			1	5.85	.016
P-ErbB-2			1	2.02	.15			1	3.32	.069
ErbB-2 × CAF			2	8.35	.015			2	14.97	.0006
P-ErbB-2 × CAF			2	1.77	.41			2	2.58	.28

NOTE. Variables included in the multivariate model included dose, square of the number of positive axillary lymph nodes, tumor size, menopausal status, and ErbB-2 or P-ErbB-2 status. For ErbB-2 immunohistochemical assay, n = 910. ErbB-2×CAF and P-ErbB-2 × CAF indicate tests of the interaction of ErbB-2 and P-ErbB-2 status, respectively (as dichotomous variables), with dose of CAF. Bold font indicates statistical significance.

Abbreviations: DFS, disease-free survival; OS, overall survival; RR, risk ratio; CAF, cyclophosphamide, doxorubicin, and fluorouracil.