Table 1.
Characteristics of women with breast cancer and their matched controls
| Variablea | Cases of cancer (n = 252) | Controls (n = 252) |
| Hypothesised risk factors | ||
| Absolute breast volume FA (ml; median (IQR)) | 63.17 (88.54) | 52.99 (68.38) |
| Relative breast volume FA (%; median (IQR)) | 2.70 (3.63) | 2.49 (2.91) |
| Other potential risk factors/confounders | ||
| BMI (n = 503; mean (SD)) | 23.8 (3.11) | 23.9 (3.22) |
| Height (cm; mean (SD)) | 161.7 (6.10) | 159.7 (5.88) |
| Age at menarche (years; n = 503; mean (SD)) | 13.0 (1.61) | 13.6 (1.68) |
| Age at 1st pregnancy (years; n = 400; mean (SD)) | 25.4 (4.19) | 23.9 (4.31) |
| Number of pregnancies (n = 503; median (IQR)) | 2 (2) | 2 (2) |
| Family history | 68 (27%) | 32 (13%) |
| Mean breast volume (ml; median (IQR)) | 569 (388) | 582 (370) |
| Parenchyma type: right breast | ||
| N1 | 21 (8%) | 54 (21%) |
| P1 | 42 (17%) | 33 (13%) |
| P2 | 65 (26%) | 40 (16%) |
| DY | 124 (49%) | 125 (50%) |
| Parenchyma type: left breast | ||
| N1 | 21 (8%) | 55 (22%) |
| P1 | 42 (17%) | 33 (13%) |
| P2 | 65 (26%) | 43 (17%) |
| DY | 124 (49%) | 121 (48%) |
| Menopausal status (n = 482) | ||
| Pre | 99 (41%) | 76 (32%) |
| Peri | 44 (18%) | 49 (20%) |
| Post | 100 (41%) | 114 (48%) |
| Age at menopause (years; n = 212; median (IQR)) | 50 (4) | 47 (6) |
Values are numbers (percentages) unless stated otherwise. aIncomplete total is indicated in brackets where there are missing data. Absolute breast volume fluctuating asymmetry (FA) = unsigned values (|L - R|) of breast volume. Relative breast volume FA = 100 × |L - R| breast volume/[|L + R| breast volume] 0.5. BMI, body mass index; IQR, inter-quartile range; SD, standard deviation.