Table 2.

Univariate and multivariable analysis of breast cancer–specific survival according to pathological tumor size, node status, posttreatment Ki67, posttreatment ER status, and posttreatment tumor grade in the P024 trial^*

Factor definition	No. of patients in each group	No. of events/no. of patients	Breast cancer–specific mortality
			Univariate analysis		Multivariable analysis
			HR (95% CI)	P	HR (95% CI)	P
Pathological tumor size†
T1/2 vs T3/4	138/33	24/171	3.5 (1.5 to 8.3)	.004	4.4 (1.7 to 11.3)	.002
T1 vs T2–4	53/118	24/171	4.1 (1.2 to 13.8)	.025	—
Node status (positive vs negative)	90/69	22/159	4.6 (1.4 to 15.8)	.01	3.2 (0.9 to 11.2)	.07
Ki67 level, per 2.7-fold increase‡	NA	25/174	1.4 (1.1 to 1.7)	.009	1.4 (1.1 to 1.8)	.02
ER, Allred score (0 or 2 vs 3–8)§	16/157	25/173	4.3 (1.6 to 11.7)	.005	6.3 (2.1 to 18.7)	<.001
Clinical response (yes vs no)	70/104	25/174	2.2 (0.97 to 4.9)	.06	1.1 (0.5 to 2.5)	.78
Grade (I vs II/III)	33/126	24/159	7.1 (0.96 to 53)	.05	4.62 (0.6 to 35.0)	.1

^*The total number in each univariate analysis varied depending on the number of tumors in which information on the individual factor was available. Cox proportional hazards model was used to calculate hazard ratios (HRs) and their confidence intervals (CIs) of relapse, comparing tumors with the adverse factor relative to those without the adverse factor. Two-sided P values are provided throughout.

^†Tumor size was examined by two cutoffs, pT1/2 vs pT3/4 and pT1 vs pT2–4. A cutoff of pT1/2 provided the smallest univariate P value and was used in the multivariable analysis (which excluded factors with a univariate P value of >.05).

^‡Ki67 analyzed as the natural-logarithm values, or per 2.7-fold increase according to the original scale of percentage values.

^§The estrogen receptor (ER) analysis refers to the posttreatment values; before treatment all the tumors in this dataset were ER+.