Antioxidants and breast cancer risk- a population-based case-control study in Canada

BMC Cancer

Table 1 Comparison of cases and controls on demographics and potential confounding factors, NECSS, Canada, 1994-1997

	Premenopausal			Postmenopausal
Characteristic	Cases (N = 866)	Controls (N = 845)	P	Cases(1496)	Controls (n = 1617)	P
Age (mean ± SD)	44.8 ± 6.2	43.8 ± 7.6	0.003	62.0 ± 8.5	62.7 ± 8.1	0.03
Education (years) (mean ± SD)	13.5 ± 3.1	13.6 ± 3.3	0.51	11.7 ± 3.4	11.3 ± 3.5	0.0009
Smoking pack-years (mean ± SD)	5.9 ± 9.4	5.8 ± 9.4	0.72	10.5 ± 15.0	8.8 ± 14.4	0.001
Alcohol consumption (drinks/wk) (mean ± SD))	2.9 ± 5.7	2.7 ± 5.1	0.48	3.1 ± 6.7	2.5 ± 5.6	0.01
BMI (kg/m² ) (mean ± SD)	24.7 ± 5.2	24.5 ± 4.8	0.29	26.1 ± 5.9	25.7 ± 5.5	0.03
Moderate physical Activity (frequency/month (mean ± SD))	15.9 ± 14.9	15.7 ± 14.1	0.67	18.6 ± 15.4	18.0 ± 15.9	0.28
Strenuous physical activity (frequency/month (mean ± SD))	4.8 ± 8.4	4.9 ± 8.0	0.77	3.3 ± 7.8	3.5 ± 8.1	0.42
Total energy intake (kcals/week)	12915 ± 4791	12687 ± 5440	0.35	12965 ± 5333	12775 ± 6997	0.39
Years of menstruation (mean ± SD)	32.0 ± 6.2	30.9 ± 7.7	0.001	33.0 ± 7.7	32.4 ± 7.6	0.02
Age at menarche (mean ± SD)	12.6 ± 1.4	12.8 ± 1.5	0.005	12.8 ± 1.6	13.0 ± 1.7	0.01
Marital status			0.89			< 0.0001
Marred	659	621		1003	1057
Common law	51	44		19	27
Divorced/separated	74	97		136	129
Windowed	16	18		248	340
Single	60	59		86	59
Other	4	4		2	2
No. live birth			0.27			< 0.0001
0-	162	168		230	174
1-	118	107		153	143
2-	366	330		400	395
3-	162	146		338	319
≥ 4	56	93		372	581
Family income adequacy			0.05			0.17
Low	102	111		283	306
Low middle	146	138		234	276
Upper middle	274	259		302	317
High	202	155		217	199
Smoking status			0.72			0.006
Never	409	413		697	826
Ex-smoker	267	221		488	505
Current smoker	190	211		311	286

ISSN: 1471-2407