Table 1.
Age-adjusted characteristics of women in the study (NHS and NHSII) at the time of the mammogram, by aspirin intake
| Characteristic | Premenopausal women | Postmenopausal women | ||||
|---|---|---|---|---|---|---|
| Non-users (n=867) | Past users (n=363) | Current users (n=463) | Non-users (n=481) | Past users (n=602) | Current users (n=899) | |
| Mean (SD) | ||||||
| Percent mammographic density | 38.9 (18.2) | 39.4 (19.3) | 40.1 (19.3) | 25.7 (18.1) | 26.2 (17.9) | 25.3 (17.7) |
| Dense area (cm2) | 43.9 (25.7) | 45.2 (26.3) | 48.9 (30.6) | 35.3 (26.4) | 37.4 (27.8) | 37.3 (28.5) |
| Non-dense area (cm2) | 78.5 (50.5) | 82.1 (59.2) | 84.2 (57.6) | 123.1 (71.1) | 128.6 (79.2) | 133.1 (80.7) |
| Age (years)* | 44.8 (4.4) | 46.7 (4.1) | 47.5 (4.2) | 54.6 (8.2) | 58.8 (7.4) | 59.3 (7.6) |
| Age at menarche (years) | 12.5 (1.4) | 12.2 (1.3) | 12.5 (1.4) | 12.5 (1.4) | 12.5 (1.5) | 12.4 (1.4) |
| Age at menopause (years) | - | - | - | 47.4 (5.9) | 47.6 (5.9) | 47.4 (6.2) |
| Body Mass Index (kg/m2) | 25.7 (5.4) | 25.6 (6.2) | 25.6 (5.2) | 26.4 (5.6) | 26.2 (5.2) | 26.0 (5.2) |
| Alcohol consumption, g/day | 4.1 (7.1) | 4.1 (6.2) | 5.7 (9.3) | 4.8 (8.8) | 4.8 (8.2) | 5.7 (8.7) |
| Percentages | ||||||
| Parity/age at first birth | 26.2 (4.3) | 26.1 (4.3) | 25.9 (4.2) | 25.0 (3.5) | 25.1 (3.6) | 25.0 (3.2) |
| Nulliparous | 15 | 15 | 10 | 10 | 9 | 8 |
| Parous, age<25 years | 32 | 34 | 36 | 44 | 46 | 49 |
| Parous, age≥25 years | 52 | 51 | 53 | 44 | 44 | 43 |
| Family history of breast cancer | 10 | 7 | 9 | 13 | 12 | 12 |
| Benign breast disease | 19 | 16 | 17 | 21 | 23 | 22 |
| Never used HT | - | - | - | 38 | 35 | 36 |
| Past HT use | - | - | - | 18 | 19 | 19 |
| Current HT use | - | - | - | 44 | 45 | 45 |
Abbreviations: SD – standard deviation; HT – postmenopausal hormone therapy
*
Value not age adjusted