Table 4.

Stratified multivariable analysis of relative survival (N = 77 708)^*

Variable	Estrogen receptor–positive status			Estrogen receptor–negative status
	No.	HR† (95% CI)	P	No.	HR (95% CI)	P
Younger (18–49 y), stage (I, II)	11 585	0.79 (0.58 to 1.08)	.15	4854	0.69 (0.53 to 0.89)	.005
Younger (18–49 y), stage (III)	1919	0.88 (0.62 to 1.26)	.51	1280	1.03 (0.74 to 1.43)	.83
Middle (50–59 y), stage (I, II)	11 508	0.65 (0.39 to 1.09)	.11	3843	0.64 (0.42 to 0.96)	.03
Middle (50–59 y), stage (III)	1549	0.47 (0.26 to 0.86)	.01	931	1.06 (0.73 to 1.56)	.73
Older (60–90 y), stage (I, II)	29 589	0.61 (0.35 to 1.08)	.10	6390	0.75 (0.45 to 1.23)	.26
Older (60–90 y), stage (III)	3066	0.73 (0.45 to 1.18)	.21	1194	0.73 (0.45 to 1.17)	.20

^*Estrogen receptor unknown and stage 0 were not included in this analysis. All P values were calculated using general linear model. All statistical tests were two-sided. CI = confidence interval; HR = hazard ratio.

^†Hazard ratios for survival among patients who did or did not undergo contralateral prophylactic mastectomy, adjusted for number of positive lymph nodes, tumor grade, race, tumor histology, and first tumor indicator.