Table 3. (a–c) The risk of invasive ductal carcinoma, with different prognostic characteristics following the use of HRT.

(a)
	No of cases	Receptor status positive	No of cases	Receptor status negative	No of cases	Low malignancy grade (grade 1)	No. of cases	High malignancy grade (grade 2+3)
HRT use	N=126/10 874	RR (95% CI)a	N=32/10 874	RR (95% CI)b	N=60/10 874	RR (95% CI)c	N=101/10 874	RR (95% CI)c
Never/past	63	1.00	25	1.00	26	1.00	63	1.00
Current	63	3.29 (2.27–4.77)	7	0.99 (0.42–2.36)	34	4.13 (2.43–7.01)	38	2.17 (1.42–3.30)
Current users pos vs neg receptor.status: P=0.013					Current users low vs high malignancy grade: P=0.063
Never	54	1.00	19	1.00	22	1.00	52	1.00
Past	9	0.65 (0.32–1.31)	6	1.30 (0.48–3.55)	4	0.70 (0.24–2.03)	11	0.82 (0.43–1.58)
Current oestrogen	11	2.52 (1.31–4.84)	1	0.70 (0.09–5.22)	2	1.07 (0.25–4.56)	10	2.49 (1.26–4.91)
E+ prog-P Cyclical	15	4.78 (2.60–8.79)	0	na	10	7.62 (3.50–16.57)	4	1.50 (0.53–4.22)
E+ test-P Cyclical	19	2.63 (1.52–4.55)	4	1.62 (0.53–4.95)	9	2.85 (1.28–6.35)	15	2.27 (1.25–4.13)
E+ test-P Continuous	12	4.28 (2.22–8.24)	2	2.27 (0.52–9.90)	9	7.87 (3.59–17.28)	6	2.51 (1.07–5.87)
Current Tibolone	2	3.22 (0.78–13.25)	0	na	1	3.78 (0.51–28.10)	2	3.45 (0.84–14.21)
Current other HRT	4	1.86 (0.67–5.15)	0	na	3	3.34 (0.99–11.23)	1	0.51 (0.07–3.67)
(b)
	No. of cases	Lymph node status negative	No. of cases	Lymph node status positive	No. of cases	Small tumour size (<2 cm)	No. of cases	Large tumour size (>2 cm)
HRT use	N=93/10 874	RR (95% CI)d	N=72/10 874	RR (95% CI)e	N=97/10 874	RR (95% CI)b	N=70/10 874	RR (95% CI)c
Never/past	48	1.00	41	1.00	52	1.00	40	1.00
Current	45	2.58 (1.67–4.00)	31	2.52 (1.32–4.83)	45	2.57 (1.67–3.97)	30	2.74 (1.67–4.50)
Current users neg vs pos lymph node status: P=0.95					Current users small vs large tumour size: P=0.86
Never	37	1.00	37	1.00	44	1.00	32	1.00
Past	11	1.11 (0.54–2.22)	4	0.26 (0.04–1.99)	8	0.83 (0.39–1.77)	8	0.95 (0.44–2.06)
Current oestrogen	6	1.86 (0.78–4.42)	5	1.89 (0.55–6.47)	5	1.47 (0.58–3.74)	6	2.41 (1.00–5.78)
E+ prog-P cyclical	8	3.03 (1.33–6.92)	7	3.11 (1.13–8.55)	8	2.77 (1.22–6.27)	7	4.40 (1.88–10.29)
E+ test-P cyclical	16	2.48 (1.31–4.68)	9	1.54 (0.60–3.98)	17	2.32 (1.23–4.36)	8	2.02 (0.90–4.51)
E+ test-P continuous	9	4.02 (1.86–8.70)	8	3.69 (1.24–10.98)	7	3.42 (1.53–7.68)	9	6.24 (2.94–13.22)
Current Tibolone	3	6.50 (1.99–21.18)	1	4.13 (0.55–31.17)	4	8.50 (3.03–23.82)	0	Na
Current other HRT	3	1.31 (0.31–5.45)	1	1.26 (0.17–9.52)	4	1.91 (0.59–6.21)	0	Na
(c)
	No. of cases	Low stage (stage 1)	No. of cases	High stage (stage 2–4)	No. of cases	NPI good prognosis	No. of cases	NPI moderate/poor prognosis
HRT use	N=65/10 874	RR (95% CI)d	N=97/10 874	RR (95% CI)c	N=60/10 874	RR (95% CI)b	N=92/10 874	RR (95% CI)c
Never/Past	33	1.00	55	1.00	30	1.00	54	1.00
Current	32	2.49 (1.49–4.18)	42	2.71 (1.77–4.13)	30	2.61 (1.52–4.47)	38	2.48 (1.60–3.84)
Current users low stage vs high stage: P=0.81					Current users good prognosis vs mod./poor: P=0.89
Never	26	1.00	47	1.00	24	1.00	46	1.00
Past	7	1.08 (0.47–2.52)	8	0.65 (0.31–1.38)	6	1.11 (0.45–2.74)	8	0.67 (0.31–1.41)
Current oestrogen	3	1.27 (0.38–4.22)	7	1.88 (0.85–4.18)	1	0.50 (0.07–3.70)	9	2.45 (1.20–5.03)
E+ prog-P cyclical	6	2.86 (1.077.57)	9	3.68 (1.76–7.71)	7	4.56 (1.93–10.78)	7	2.88 (1.27–6.52)
E+ test-P cyclical	12	2.54 (1.23–5.26)	13	2.17 (1.14–4.11)	12	2.47 (1.13–5.41)	11	1.83 (0.92–3.62)
E+ test-P continuous	5	3.36 (1.28–8.80)	11	5.11 (2.62–9.94)	5	3.90 (1.48–10.28)	9	4.29 (2.08–8.84)
Current Tibolone	3	8.61 (2.59–28.61)	1	1.93 (0.27–14.04)	2	7.03 (1.65–29.85)	1	1.97 (0.27–14.32)
Current other HRT	3	1.76 (0.42–7.45)	1	0.56 (0.08–4.10)	3	2.13 (0.50–9.05)	1	0.57 (0.08–4.14)

E=oestrogen, P=progestin, prog-P= progesterone-like progestin, test-P=testosterone-like progestin. NPI= Nottingham Prognostic Index.

^aAdjusted for age, benign breast disease (0, yes; 1, no).

^bAdjusted for age, age at menopause.

^cAge adjusted.

^dAdjusted for age, age at menopause (0<55 years; 1, 55+years) and use of oral contraceptives (0, no; 1, yes).

^eAdjusted for age and night work (0, no; 1, yes).