Table 1 Percentage distributions or means (standard deviation, SD) of cases with breast cancer and their controls by study characteristics in the HSHS cohort
From: Oral contraceptive use before first birth and risk of breast cancer: a case control study
Study characteristic | Percentage or mean | |
|---|---|---|
Cases n = 150 | Controls n = 316 | |
Year of birth, % | ||
1946–1950 | 48 | 47 |
1951–1955 | 29 | 30 |
1956–1960 | 23 | 24 |
First visit at the HSHS, % | ||
1965–1969 | 19 | 14 |
1970–1974 | 39 | 41 |
1975–1995 | 43 | 45 |
Smoking, % | ||
Current | 23 | 29 |
Quitted | 3 | 6 |
Never | 58 | 55 |
No information | 16 | 10 |
Alcohol use, % | ||
Moderate or heavy | 17 | 18 |
Slight | 37 | 38 |
No | 9 | 15 |
No information | 37 | 29 |
Sports, % | ||
Active | 21 | 35 |
No | 53 | 44 |
No information | 26 | 21 |
Weight (kg), mean (SD) | 57.0 (7.1) | 56.2 (7.6) |
Height (cm), mean (SD) | 166 (5.2) | 165 (5.6) |
Age at menarche (in years), mean (SD) | 12.8 (1.2) | 12.7 (1.2) |
Contraception *, % | 94 | 88 |
Any births ‡, % | 73 | 67 |
Age at first delivery § (in years), % | ||
18–24 | 17 | 20 |
25–29 | 48 | 49 |
30–34 | 29 | 26 |
35–41 | 5 | 5 |
Mean (SD) | 28.1 (3.7) | 27.7 (4.1) |