Table 2.
Differences in mammographic density by selected risk factors among premenopausal women (MTC, 2006)
| Percent densitya | Ln dense area (cm2) a,b | Ln non-dense area (cm2) a,c | |
|---|---|---|---|
|
| |||
| Age (years) | −0.38 (−0.60,−0.16) | −0.017 (−0.027,−0.007) | 0.004 (−0.002,0.009) |
| BMI (kg/m2) | −0.40 (−0.58,−0.21) | 0.028 (0.018,0.038) | 0.048 (0.043,0.052) |
| BMI at age 18 (kg/m2)^∨ | −0.68 (−0.99,−0.37) | 0.014 (−0.001,0.029) | 0.054 (0.047,0.062) |
| Weight change since age 18 (lbs)^ | −0.13 (−0.21,−0.05) | 0.012 (0.008,0.016) | 0.019 (0.017,0.021) |
| Nulliparity | −0.23 (−2.99,2.53) | −0.119 (−0.237,−0.001) | −0.098 (−0.168,−0.029) |
| Number of children among parous* | −0.62 (−1.72,0.48) | −0.018 (−0.065,0.029) | 0.005 (−0.022,0.032) |
| Family history of breast cancer | −0.02 (−4.00,3.96) | 0.041 (−0.131,0.214) | 0.029 (−0.070,0.128) |
| History of BBD | 4.56 (2.03,7.08) | 0.152 (0.042,0.261) | −0.062 (−0.125,0.001) |
| Indigenous language/dialect | −0.91 (−5.40,3.58) | −0.018 (−0.212,0.177) | −0.015 (−0.127,0.098) |
| Age at menarche | |||
| <12 | Ref | Ref | Ref |
| 12 | 1.63 (−0.79,4.05) | 0.052 (−0.053,0.157) | −0.022 (−0.083,0.038) |
| 13 | −0.63 (−3.17,1.90) | −0.077 (−0.187,0.033) | −0.010 (−0.073,0.054) |
| 14+ | 0.87 (−1.68,3.42) | −0.011 (−0.121,0.100) | −0.018 (−0.082,0.045) |
| Age at first pregnancy* | |||
| <25 | Ref | Ref | Ref |
| 25+ | −0.84 (−2.88,1.20) | 0.014 (−0.074,0.101) | 0.042 (−0.009,0.093) |
| Breastfeeding* | |||
| Never | Ref | Ref | Ref |
| <12 months | 1.37 (−1.81,4.56) | 0.082 (−0.053,0.218) | 0.014 (−0.065,0.092) |
| 12+ months | 3.78 (0.51,7.05) | 0.122 (−0.017,0.262) | −0.030 (−0.111,0.050) |
| Hormonal contraceptives | |||
| Never | Ref | Ref | Ref |
| Past | −0.52 (−2.56,1.52) | −0.034 (−0.123,0.054) | −0.007 (−0.057,0.044) |
| Current | 1.46 (−4.27,7.20) | 0.121 (−0.128,0.369) | 0.062 (−0.080,0.204) |
| Alcohol use | |||
| No | Ref | Ref | Ref |
| Yes | 2.26 (0.25,4.26) | 0.141 (0.054,0.229) | 0.021 (−0.029,0.072) |
Adjusted for age (continuous), state (Jalisco, Veracruz), BMI (continuous), BMI at age 18 (continuous), nulliparity (yes, no), parity among parous (continuous), family history of breast cancer (yes, no), history of BBD (yes, no), indigenous language/dialect (yes, no), age at menarche (<12, 12, 13, 14+), age at first pregnancy (<25, 25+, unknown), breastfeeding among parous (never, <12 months, 12+ months, unknown), hormonal contraceptives (never, past, current, ever – current status unknown, unknown), alcohol (no, yes)
Further adjusted for non-dense area
Further adjusted for dense area
among parous
not adjusted for current BMI
further adjusted for weight change since age 18