Case-control study of tobacco smoke exposure and breast cancer risk in Delaware

BMC Cancer

Table 1 Selected characteristics of breast cancer cases and controls, Delaware, 2000–2002

	cases (n = 287)		controls (n = 311)
Characteristic	n	%	n	%	p-value^a
Age at interview (years)
40–49	53	18.5	63	20.3
50–59	74	25.8	94	30.2
60–69	87	30.3	77	24.8
70–80	73	25.4	77	24.7	0.32
Race
White	264	92.0	294	94.5
Black/Other	23	8.1	17	5.5	0.21
Education^b
<12 grades	30	10.5	14	4.5
12 grades	114	39.9	108	37.8
some college	108	37.8	148	47.6
post-college	34	11.9	41	13.2	< 0.01
Menopausal status
premenopausal	30	10.5	65	20.9
postmenopausal	257	89.6	246	79.1	< 0.01
Body mass index (kg/m2)^b
15–24	107	37.3	122	39.6
25–29	102	35.5	114	37.0
30–88	78	27.2	72	23.4	0.56
Age at menarche (years)^b
8–12	140	49.3	142	45.8
13–18	144	50.7	168	54.2	0.39
Number of Live Births^b
nulliparous^c	44	15.3	35	11.3
1–2	128	44.6	145	46.8
3–4	97	33.8	112	36.1
5–11	18	6.3	18	5.8	0.52
Age at 1st live birth (years)^b
< 30	219	90.1	242	88.0
30+	24	9.9	33	12.0	0.44
Oral contraceptive use
Never	120	41.8	110	35.4
Ever	167	58.2	201	64.6	0.11
Other hormone use^b
Never	153	53.3	161	51.9
Ever	134	46.7	149	48.1	0.74
Family History of Breast Cancer^b,c
No	220	77.7	257	82.9
Yes	63	22.3	53	17.1	0.11
Alcohol consumption
< 12 drinks in lifetime	37	12.9	49	15.8
≥ 12 drinks in lifetime, but never had ≥ 1 drink per mo. for ≥ 6 mos	87	30.3	85	27.3
drank ≥ 1 drink per mo. for ≥ 6 mos	163	56.8	177	56.9	0.52

^a p-values based on chi-square test; p-values based on Mantel-Haenszel chi-square test for trend for the following variables: age, education, BMI, and age at first live birth
^b Numbers do not always sum to total number of cases and/or controls due to missing information
^c Includes 9 cases and 10 controls who reported 1+ pregnancies
^d Family history of breast cancer defined as mother or sister ever diagnosed with breast cancer

ISSN: 1471-2407