Comparisons of cases and controls on demographics and selected breast cancer risk factors (Shanghai Breast Cancer Study, 1996-1999)
| Characteristics | Cases (n = 1,459) | Controls (n = 1,556) | P | |||
|---|---|---|---|---|---|---|
| Age | 47.93 ± 7.99 | 47.25 ± 8.79 | 0.24 | |||
| Education(%) | ||||||
| No formal education | 3.63 | 5.46 | ||||
| Elementary school | 8.50 | 8.42 | ||||
| Middle + high school | 74.3 | 75.4 | ||||
| Profession, college and above | 13.6 | 10.7 | 0.012 | |||
| Breast cancer in first-degree relatives (%) | 3.7 | 2.4 | 0.045 | |||
| Ever had breast fibroadenoma (%) | 9.6 | 5.0 | <0.001 | |||
| Nulliparous (%) | 5.1 | 3.9 | 0.126 | |||
| Age at first live birth (y) | 26.7 ± 4.2 | 26.2 ± 3.9 | <0.01 | |||
| Menarcheal age (y) | 14.5 ± 1.6 | 14.7 ± 1.7 | <0.01 | |||
| Postmenopausal (%) | 34.5 | 36.2 | 0.321 | |||
| Menopausal age (y)* | 48.1 ± 4.6 | 47.4 ± 4.9 | 0.02 | |||
↵* Among postmenopausal women only.