Table 3.

Risk of breast cancer-specific death according to ER status (ER-positive vs ER-negative) for short (0–5 years) and long (5+ years) periods from diagnosis.

	0–5 years from diagnosis		5+ years from diagnosis
	HRa (95% CI; P value)	P-value interaction	HRa (95% CI; P value)	P-value interaction
Age
>50 y	0.46 (0.21–1.01; 0.05)		1.48 (0.75–2.91; 0.25)
≤50 y	0.45 (0.22–0.91; 0.03)	0.98	1.91 (1.06–3.43; 0.03)	0.32
Endocrine treatment
Yes	0.18 (0.08–0.43; <0.001)	0.01	0.72 (0.32–1.61; 0.43)	0.01
No	0.73 (0.33–1.63; 0.45)		2.36 (1.26–4.44; 0.01)
Bilateral oophorectomy
Yes	0.03 (0.00–0.29; <0.01)	0.01	0.61 (0.20–1.81; 0.37)	0.03
No	0.65 (0.33–1.27; 0.20)		1.99 (1.11–3.59; 0.02)
Chemotherapy
Yes	0.31 (0.14–0.68; <0.01)	0.10	1.41 (0.73–2.72; 0.37)	0.23
No	0.75 (0.31–1.81; 0.20)		2.40 (1.10–5.28; 0.02)
BRCA2 mutation location
O + Bb	0.63 (0.32–1.25; 0.19)	0.01	2.23 (1.21–4.10; 0.01)	0.01
Other	0.07 (0.02–0.36; <0.01)		0.56 (0.22–1.44; 0.24)

Stratification by age, endocrine treatment, bilateral oophorectomy, chemotherapy and mutation location. Also shown are P values for interaction between ER status and the respective variable.

^aMultivariate HR comparing ER+ with ER−, adjusting for other stratification variables in the table and also for year of diagnosis, size, lymph node status and prophylactic mastectomy.

^bOvarian cancer cluster regions (OCCRs) and breast cancer cluster regions (BCCRs).