Table 2.

Cox Proportional Hazards Regression Model^a assessing interaction of recurrence score (RS) risk group (Grouping Method I) with chemotherapy effect, excluding patients with HER2-positive disease

n = 564 patients
Effect	Hazard ratio (95% Confidence interval)	Likelihood ratio test on interaction, P value
Chemotherapy in RS < 18	1.19 (0.40–3.49)	0.023
Chemotherapy in RS from 18–30	0.64 (0.23–1.75)
Chemotherapy in RS ≥ 31	0.18 (0.07–0.46)

^a Adjusting for patient age (>50 vs. ≤50 years), clinical tumor size (>2.0 vs. ≤2.0 cm), ER by ligand binding assay (≥100 vs. <100 fmol/mg), PR by ligand binding assay (≥100 vs. <100 fmol/mg), and tumor grade (well differentiated, moderately differentiated, and poorly differentiated). Five (5) patients had missing values in tumor grade or tumor size.