Table 1 Characteristics of the study population in the Polish Breast Cancer Study
From: Established breast cancer risk factors by clinically important tumour characteristics
Cases | Controls | |
|---|---|---|
Study characteristic | N=2386 | N=2502 |
Age in years (mean±s.d.) | 55.8±10.0 | 55.9±10.1 |
Study site (% Warsaw) | 65 | 63 |
Education level (% college degree) | 25 | 15 |
Marital status (% married) | 62 | 63 |
Age at menarche in years (mean±s.d.) | 13.5±1.7 | 13.7±1.7 |
Parity (% parous) | 86 | 89 |
Number of full-term births (mean±s.d.) | 1.7±0.8 | 1.9±0.8 |
Age at first full-term birth (mean±s.d.) | 24.5±4.6 | 23.6±4.2 |
Breastfeeding among women with live births (% ever) | 78 | 81 |
Oral contraceptive use (% ever) | 12 | 10 |
Menopausal status (% postmenopausal) | 75 | 70 |
Type of menopause among postmenopausal women (% natural) | 77 | 84 |
Age at menopause (mean±s.d.) | 49.6±4.6 | 49.2±5.0 |
Use of oral HRT among postmenopausal women (% ever) | ||
Never | 77 | 83 |
Current use of combined therapy (<6 months) | 7 | 4 |
Recent use of combined therapy (6 months–<2 years) | 4 | 2 |
Past use of combined therapy (last use 2 or more years ago) | 4 | 5 |
Ever used E or P alone | 7 | 7 |
Duration of combined HRT among current/recent users (mean±s.d.) | 11.1±12.5 | 9.7±10.7 |
Current BMI among premenopausal (mean±s.d.) | 25.4±4.9 | 26.4±5.1 |
Current BMI among postmenopausal (mean±s.d.) | 27.9±5.4 | 28.6±5.4 |
Alcohol consumption (% ever) | 33 | 32 |
Family history of breast cancer in first-degree relatives (%) | 10 | 6 |
Prior benign breast bipospy (%) | 10 | 6 |
Ever had a screening mammogram (%) | 62 | 54 |
