Table 3.

Stratified 5 Year Cumulative Incidences

		5 Year Cumulative Incidence of Mastectomy CI (95% Confidence Interval)			5 year Cumulative Incidence of Breast cancer death CI (95% Confidence Interval)
Age Group	N	RT	No RT	P	RT	No RT	P
70-74	93	4.0% (2.8%- 5.8%	12.6% (6.6%- 23.9%)	0.002	5.6% (4.0%- 7.7%)	14.8% (9.3%- 23.6%)	0.001
75-79	116	3.8% (2.5%- 5.8%)	10.2% (5.2%- 20.1%)	0.003	7.3% (5.6%- 9.5%)	17.2% (10.6%- 27.6%)	0.001
80+	373	3.4% (2.1%- 5.7%)	6.9% (4.0%- 12.1%)	0.05	9.5% (7.3%- 12.4%)	21.4% (15.9%- 28.9%)	<0.001
T Stage
T1	377	5.3% (3.1%- 5.2%)	7.7% (5.1%- 11.6%)	0.01	5.3% (4.2%- 6.5%)	12.5% (9.1%- 17.2%)	<0.001
T2	205	4.24% 95% CI: 2.64%-6.81%	9.92% 95% CI: 6.15%-15.98%	0.01	14.2% (11.2%- 18.0%)	28.9% (22.9%- 36.5%)	<0.001