Table 3.

Effect of radiotherapy by HER2 status.

Endpoint	Subgroup	n	Eventsa	HR (95% CI)	P	P het
IBE	HER2 negative	468	71	0.47 (0.27–0.82)	0.0048	0.07
	HER2 positive	245	76	0.21 (0.10–0.42)	<0.0001
I-IBE	HER2 negative	468	33	0.36 (0.15–0.87)	0.023	0.98
	HER2 positive	245	21	0.35 (0.12–1.05)	0.062
DCIS-IBE	HER2 negative	468	38	0.58 (0.28–1.19)	0.14	0.04
	HER2 positive	245	53	0.16 (0.07–0.41)	0.0001

Note: Subgroups: HER2 positive (3+) and HER2 negative (0, 1+, and 2+).

^aRecurrence type not known in two cases.