Table 1. Baseline characteristics of 2640 postmenopausal Swedish women diagnosed with breast cancer in 1993–1995, by body mass index.

	BMI
	<25	25–30	>30	P-value
No. of cases	1267	997	376
Mean
Age at diagnosis (years)	62.4	64.0	64.7	<0.0001
Parity	1.8	1.9	1.8	0.34
Age at first birth (years)	25.5	25.3	25.3	0.68
Age at menopausea (years)	50.5	50.7	50.4	0.88
Current alcohol intake, g day−1	2.9	2.3	1.7	<0.0001
Frequency (%)
High socioeconomic statusb	54	47	39	<0.0001
Ever HRT
Ever oestrogen alone	14	10	7	0.0005
Ever oestrogen–progestin	30	15	12	<0.0001
Current smoker	30	18	13	<0.0001
Recent mammographyc	65	60	64	0.64
Detection by screening	57	63	65	0.012
Primary treatment
Surgery	99	100	99	0.86
Chemotherapy	8	9	11	0.15
Antioestrogenic therapy	54	51	57	0.30
Radiotherapy	64	62	63	0.96
Deceased at end of follow-up	24	24	35	0.0003
Cause of death
Breast cancer	15	15	21	0.0008
Other cause	9	9	14	0.0014

BMI=body mass index (kg m⁻²); HRT=hormone replacement therapy.

P-value: two sided t-test for means and χ²-test for the frequencies comparing BMI >30 vs BMI <25.

^aAmong women with a natural menopause.

^bHigh level includes medium- and high-level white collar workers.

^cMammography within 2 years and 2 months before diagnosis.