Vitamin D receptor gene polymorphisms and haplotypes and postmenopausal breast cancer risk

Breast Cancer Research

Table 1 Characteristics and risk factors for postmenopausal breast cancer in cases and matched controls in the study population

Characteristics	Cases (n^a = 1,408)		Controls (n^a+ = 2,612)		P ^b
	n	%	n	%
Age at diagnosis/recruitment (years)					0.87
50 to 54	104	7.4	191	7.3
55 to 59	301	21.4	528	20.2
60 to 64	447	31.7	859	32.9
65 to 69	380	27.0	720	27.6
≥70	176	12.5	314	12.0
BMI (kg/m²)					0.68
< 22.5	554	39.4	1,043	39.9
22.5 to < 25	473	33.6	829	31.8
25 to < 30	323	22.9	624	23.9
≥30	58	4.1	114	4.4
Educational level					0.07
Low	912	64.8	1,761	67.4
Middle	305	21.6	559	21.4
High	191	13.6	292	11.2
Age at menopause (years)					< 0.01
< 47	146	10.4	396	15.2
47 to 51	407	28.9	748	28.6
52 to 55	248	17.6	402	15.4
≥56	63	4.5	115	4.4
Unknown	544	38.6	951	36.4
First degree family history of breast cancer					< 0.01
No	1,113	79.1	2,164	82.8
Yes	234	16.6	329	12.6
Unknown	61	4.3	119	4.6
Benign breast disease					< 0.01
No	860	61.3	1,833	70.5
Yes	544	38.7	766	29.5
Number of pregnancies (≥ 28^th week)					< 0.01
0	200	14.2	294	11.3
1	383	27.2	635	24.3
2	518	36.8	1,031	39.5
≥3	307	21.8	652	24.9
Age at menarche (years)					0.02
< 12	125	8.9	221	8.5
12 to 14	950	67.5	1,658	63.7
≥15	333	23.6	725	27.8
Ever breastfeeding					< 0.01
No	555	39.4	868	33.2
Yes	853	60.6	1,744	66.8
Number of mammograms in total					< 0.01
0	195	13.8	334	12.8
1 to 4	598	42.5	1,370	52.5
5 to 9	343	24.4	599	22.9
≥10	254	18.0	288	11.0
Unknown number	18	1.3	21	0.8
Use of hormone therapy					< 0.01
Never	528	37.9	1,113	43.1
Past	293	21.0	672	26.0
Current (≤ 6 months)	572	41.1	798	30.9
Hormonal receptor status of the tumor^c
ER-positive	994	76.3
ER-negative	308	23.7
PR-positive	848	65.2
PR-negative	453	34.8
Time of blood collection^d					0.99
January to March	317	22.8	311	22.8
April to June	292	21.0	286	21.0
July to September	402	28.9	392	28.7
October to December	380	27.3	376	27.5

^aNumbers do not always add up to total numbers because of missing values. ^bχ² test for differences between cases and controls. ^cData on estrogen receptor (ER) and progesterone receptor (PR) status was available for 1,302 and 1,301 invasive tumour cases (in situ tumours excluded), respectively. ^dData on serum 25-hydroxyvitamin D status were available for 1,391 cases and 1,365 controls. BMI, body mass index.

ISSN: 1465-542X