The association of polymorphisms in hormone metabolism pathway genes, menopausal hormone therapy, and breast cancer risk: a nested case-control study in the California Teachers Study cohort

Table 1 Characteristics of the study participants at time of joining the cohort

	Control		Case
Characteristics	Number	Percentage	Number	Percentage
Number	1,395		1,351
Mean age ± SD, years	56.1 ± 9.5		55.0 ± 9.4
Menopausal status
Premenopausal	347	25.3	364	27.5
Postmenopausal^a	1,024	74.7	962	72.5
Unknown	24	-	25	-
HT use among postmenopausal women
Never used HT	153	15.8	112	12.4
Current ET use	277	28.7	230	25.5
Current EPT use	401	41.5	468	51.9
Former ET or EPT use	122	12.6	80	8.9
Ever used progestin alone	13	1.3	12	1.3
Unknown	58	-	60	-
Parity/total number of FTPs
Nulligravid	221	16.1	219	16.4
Gravid, nulliparous	61	4.4	66	4.9
1 FTP	159	11.6	174	13.0
2 FTPs	487	35.4	472	35.3
3 FTPs	274	20.0	277	20.7
4+ FTPs	172	12.5	128	9.6
Unknown	21	-	15	-
Body mass index
< 25 kg/m²	765	54.8	778	58.9
25 to < 30 kg/m²	387	27.7	384	29.1
30+ kg/m²	195	14.0	159	12.0
Unknown	48	-	30	-
Age at menarche
≤10 years	100	7.3	100	7.5
11-12 years	600	43.6	599	44.8
13-14 years	565	41.0	542	40.6
15-16 years	102	7.4	82	6.1
17+ years	10	0.7	13	1.0
Unknown/Never had menarche	18	-	15	-
Family history of breast cancer (first-degree relative)
No	1,167	86.1	1,085	82.1
Yes	189	13.9	236	17.9
Unknown	39	-	30	-
History of breast biopsy
No	1,086	77.8	1,034	76.5
Yes	309	22.2	317	23.5
Screening mammograms within last 2 years
No	138	10.0	146	10.9
Yes	1,241	90.0	1,193	89.1
Unknown	16	-	12	-

^aIncludes perimenopausal women. EPT, estrogen progestin combined therapy; ET, estrogen therapy; FTP, full-term pregnancy; HT, hormone therapy; SD, standard deviation.

ISSN: 1465-542X