Table 1: Demographic characteristics of women who died from breast cancer or had distant metastases and matched control subjects in the Canadian National Breast Screening Study (NBSS)*
Characteristic	Group; no. (and %) of subjects		OR†(and 95% CI‡)	p value
	Cases n = 220	Controls n = 2200
Birthplace
North America	187 (85)	1885 (86)	1.00 RV§
Europe	31 (14)	270 (12)	1.17 (0.77-1.77)	0.47
Elsewhere	2 (1)	42 (2)	0.47 (0.11-2.01)	0.31
Marital status
Married	167 (76)	1778 (81)	1.00 RV
Never married	16 (7)	158 (7)	1.09 (0.63-1.87)	0.77
Separated/divorced	21 (9)	174 (8)	1.28 (0.78-2.07)	0.32
Widowed	16 (7)	90 (4)	1.93 (1.10-3.39)	0.02
Educational level completed
Elementary school	17 (8)	227 (10)	1.00 RV
High school/technical school	144 (66)	1479 (68)	1.34 (0.78-2.31)	0.29
University	56 (26)	474 (22)	1.63 (0.91-2.94)	0.11
Occupation
All others	143 (69)	1548 (76)	1.00 RV
Management/professional	64 (31)	491 (24)	1.44 (1.05-1.98)	0.02
Smoking history
Never smoked	109 (50)	1113 (51)	1.00 RV
Ever smoked	111 (50)	1083 (49)	1.05 (0.79-1.38)	0.75
Current smoker	65 (30)	469 (21)	1.42 (1.02-1.97)	0.04
Past smoker	46 (21)	614 (28)	0.76 (0.53-1.09)	0.13
Not currently smoking	155 (70)	1727 (79)	1.00 RV
Current smoker	65 (30)	469 (21)	1.55 (1.14-2.11)	0.01
Body mass index, kg/m2
<= 21	49 (22)	510 (23)	0.90 (0.63-1.27)	0.53
22-26	121 (55)	1130 (52)	1.00 RV
>= 27	50 (23)	546 (25)	0.86 (0.61-1.21)	0.37
*Missing responses were excluded. †Odds ratio estimated by conditional logistic regression. ‡95% confidence interval = antiln {ln(OR) ± 1.96 × standard error [ln(OR)]}. §RV = reference variable.

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