Table 2.

Participant and tumor characteristics among cases and controls

Participant or tumor characteristic	Total	Cases		Controls		p*
		N	%	N	%
Age (years)
≤49	470	96	41.6	374	43.7	0.84
50–59	299	66	28.6	233	27.2
≥60	318	69	29.9	249	29.1
Treatment
Placebo	605	164	71.0	441	51.5	<.0001
Tamoxifen	482	67	29.0	415	48.5
5-year predicted breast cancer risk (%)
≤2.24	300	64	27.7	236	27.6	0.99
2.25–3.48	293	63	27.3	230	26.9
≥3.49	494	104	45.0	390	45.6
Body mass index
<25.0	444	79	34.2	365	42.6	0.02
≥25.0	643	152	65.8	491	57.4
Smoking history (years)
None	592	117	50.6	475	55.5	0.33**
<18	173	35	15.2	138	16.1
18–27	143	39	16.9	104	12.1
≥28	175	39	16.9	136	15.9
Unknown	4	1	0.4	3	0.4
History of hormone use
No	273	60	26.0	213	24.9	0.73
Yes	814	171	74.0	643	75.1
No. 1° relatives with breast cancer
0	220	47	20.3	173	20.2	0.41
1	605	121	52.4	484	56.5
≥2	262	63	27.3	199	23.2
Menopausal status
Premenopausal	530	113	48.9	417	48.7	0.73
Postmenopausal	493	102	44.2	391	45.7
Unknown	64	16	6.9	48	5.6
History of breast atypical hyperplasia
No	986	204	88.3	782	91.4	0.16
Yes	101	27	11.7	74	8.6
History of osteoporosis
No	1034	216	93.5	818	95.6	0.20
Yes	53	15	6.5	38	4.4
25-Hydroxy vitamin-D concentration
<72 nmol/l	793	175	75.8	618	72.2	0.28
≥72 nmol/l	294	56	24.2	238	27.8
Type of invasive cancer
Infiltrating duct carcinoma	171	171	74.0	–	–	–
Other	60	60	26.0	–	–
Estrogen receptor status
Negative	56	56	24.2	–	–	–
Positive	158	158	68.4	–	–
Unknown	17	17	7.4	–	–
Progesterone receptor status
Negative	85	85	36.8	–	–	–
Positive	123	123	53.2	–	–
Unknown	23	23	10.0	–	–
Presenting cancer stage
I	131	131	56.7	–	–	–
II	76	76	32.9	–	–
III–IV	14	14	6.1	–	–
Unknown	10	10	4.3	–	–

* p values are from χ² test unless otherwise specified

** Fisher’s exact test