Table 2.
Conditional logistic regression analyses with presence or absence of cancer as the dependent variable, for both absolute and relative breast fluctuating asymmetry (n = 504)
| Risk factor | Crude relative odds | (95% CI) | p-value | Adjusted relative oddsa | (95% CI) | p-value | Adjusted relative oddsb | (95% CI) | p-value |
| Absolute breast FA (100 ml) | 1.29 | (1.01, 1.64) | 0.039 | 1.50 | (1.10, 2.04) | 0.010 | - | - | - |
| Relative breast FA (%) | 1.07 | (0.99, 1.14) | 0.070 | - | - | - | 1.09 | (1.01, 1.18) | 0.032 |
| BMI | 1.00 | (0.95, 1.06) | 0.98 | 1.00 | (0.91, 1.09) | 0.97 | 1.00 | (0.92, 1.09) | 0.98 |
| Height (cm) | 1.06 | (1.03, 1.09) | <0.001 | 1.06 | (1.02, 1.09) | 0.001 | 1.05 | (1.02, 1.09) | 0.002 |
| Age at menarche (years) | 0.81 | (0.72, 0.90) | <0.001 | 0.78 | (0.69, 0.89) | <0.001 | 0.78 | (0.69, 0.89) | <0.001 |
| Number of pregnancies | 0.94 | (0.84, 1.04) | 0.23 | 1.04 | (0.92, 1.18) | 0.49 | 1.04 | (0.92, 1.18) | 0.52 |
| Family history (no. of relatives) | 2.00 | (1.37, 2.94) | <0.001 | 2.08 | (1.35, 3.20) | 0.001 | 2.10 | (1.36, 3.23) | 0.001 |
| Mean breast volume (ml) | 1.00 | (0.999, 1.001) | 0.82 | 1.00 | (0.999, 1.000) | 0.33 | 1.00 | (0.999, 1.001) | 0.94 |
| Parenchyma type: right breast | |||||||||
| N1 | 1.0 | - | - | 1.0 | - | - | 1.0 | - | - |
| P1 | 3.25 | (1.62, 6.52) | 0.001 | 3.23 | (1.51, 6.91) | 0.003 | 3.30 | (1.54, 7.05) | 0.002 |
| P2 | 4.27 | (2.23, 8.17) | <0.001 | 3.61 | (1.73, 7.53) | 0.001 | 3.75 | (1.80, 7.82) | <0.001 |
| DY | 2.69 | (1.51, 4.79) | 0.001 | 2.94 | (1.48, 5.84) | 0.002 | 3.02 | (1.52, 5.99) | 0.002 |
| Menopausal status | |||||||||
| Pre | 1.0 | - | - | 1.0 | - | - | 1.0 | - | - |
| Peri | 0.49 | (0.26, 0.91) | 0.023 | 0.45 | (0.23, 0.87) | 0.017 | 0.46 | (0.24, 0.89) | 0.022 |
| Post | 0.29 | (0.14, 0.61) | 0.001 | 0.37 | (0.16, 0.83) | 0.017 | 0.38 | (0.17, 0.85) | 0.018 |
| Age at menopausec (years) | 1.16 | (1.06, 1.27) | 0.002 | 1.18 | (1.06, 1.31) | 0.002 | 1.17 | (1.06, 1.30) | 0.002 |
All variables are continuous unless otherwise indicated. aAbsolute breast FA = unsigned values (|L - R|) of breast volume. bRelative breast fluctuating asymmetry (FA) = 100 × |L - R| breast volume/[|L + R| breast volume] 0.5. cFor subgroup of post-menopausal women. When age at menopause is included in the model body mass index (BMI), height, number of pregnancies and parenchyma types P1 and P2 become insignificant, and mean breast volume and parenchyma type DY have borderline significance. Absolute breast FA and relative breast FA remain significant effects. CI, confidence interval.