Table 1. Selected characteristics of the study population.

	Cases (n=613)	%	Controls (n=1082)	%	P-valuea
Mean age (s.d.)	42.4 (5.8)		42.6 (5.7)
Menopausal status
Premenopausal	483	78.8	874	80.8
Postmenopausal	34	5.6	67	6.2
Unknown	96	15.7	141	13.0	0.30
First-degree family history
No	536	87.4	1024	94.6
Yes	77	12.6	58	5.4	<0.01
Parity
0	136	22.2	228	21.1
1–2 children	414	67.5	680	62.9
3+ children	63	10.3	174	16.1	<0.01
Breastfeeding b
0	153	32.1	247	28.9
1–12 months	289	60.6	501	58.7
12+ months	35	7.3	106	12.4	0.01
Education
Low	80	13.1	149	13.8
Intermediate	412	67.2	679	62.8
High	121	19.7	254	23.5	0.15
Smoking
Never active	271	44.2	515	47.6
Former smoker	132	21.5	258	23.8
Current smoker	210	34.3	309	28.6	0.05
Alcohol consumption (g day on average−1)
0	117	19.1	176	16.3
1–5	233	38.0	454	42.0
6–11	113	18.4	239	22.1
12+	150	24.5	213	19.7	0.02
ADH1B genotypes
*1/*1	548	89.4	973	89.9
*1/*2	62	10.1	107	9.9
*2/*2	3	0.5	2	0.2	0.53c

s.d.=standard deviation; ADH1B=alcohol dehydrogenase 1B.

^aχ² test used.

^bAmong parous women only.

^cFisher's exact test used.