Table 6.

Sensitivity analyses of chemotherapy receipt on breast cancer-specific mortality using the Cox regression model and the competing-risks model (SEER database).

Variables	Cox regression model			Competing-risks model
	HR	95%CI	P	sdHR	95%CI	P
Years 2004–2010
Intermediate RS (n = 2967)
No chemotherapy	1			1
Chemotherapy	0.824	0.513–1.325	0.425	1.009	0.395–2.578	0.985
High RS (n = 856)
No chemotherapy	1			1
Chemotherapy	0.923	0.641–1.329	0.668	1.092	0.665–1.791	0.728
Years 2011–2012
Intermediate RS (n = 2092)
No chemotherapy	1			1
Chemotherapy	2.111	0.979–4.552	0.057	4.204	0.966–18.289	0.056
High RS (n = 622)
No chemotherapy	1			1
Chemotherapy	0.717	0.355–1.449	0.355	0.848	0.319–2.253	0.741
Aged 65–69 years
Intermediate RS (n = 2816)
No chemotherapy	1			1
Chemotherapy	1.077	0.610–1.901	0.799	1.94	0.648–5.811	0.236
High RS (n = 795)
No chemotherapy	1			1
Chemotherapy	1.075	0.659–1.753	0.773	1.602	0.818–3.138	0.17
Aged 70–74 years
Intermediate RS (n = 1405)
No chemotherapy	1			1
Chemotherapy	0.739	0.319–1.710	0.48	1.511	0.409–5.584	0.536
High RS (n = 432)
No chemotherapy	1			1
Chemotherapy	0.597	0.313–1.138	0.117	0.557	0.226–1.370	0.203
Aged > 74 years
Intermediate RS (n = 838)
No chemotherapy	1			1
Chemotherapy	1.397	0.634–3.078	0.407	1.187	0.141–10.006	0.875
High RS (n = 251)
No chemotherapy	1			1
Chemotherapy	0.767	0.403–1.461	0.42	0.793	0.272–2.311	0.671

CI, confidence interval; HR, hazard ratio; RS, recurrence score; sdHR, sub-distribution hazard ratio.