Table 3.

Associations of body size and adult weight gain and risk of invasive breast cancer and hormone receptor subtypes by race/ethnicity, postmenopausal women residing in California at baseline (n = 48,247), MEC, 1993–2010

All women(n = 48,247)African American (n = 16,703)Japanese American (n = 5,063)Latino (n = 18,752)White (n = 7,729)
HR (95% Cl)HR (95% Cl)HR (95% Cl)HR (95% Cl)HR (95% Cl)
Independent of individual-level factorsa
 BMI at baseline, kg/m2
  Underweight0.83 (0.57–1.21)1.00 (0.44–2.27)0.61 (0.31–1.21)1.19 (0.53–2.69)1.00 (0.50–1.98)
  Normal1.001.001.001.001.00
  Overweight1.01 (0.89–1.14)0.85 (0.69–1.05)1.28 (0.86–1.90)1.11 (0.90–1.38)0.93 (0.71–1.22)
  Obese0.98 (0.84–1.14)0.83 (0.65–1.05)0.97 (0.41–2.34)1.20 (0.93–1.55)0.84 (0.57–1.22)
  Ptrendb0.800.150.520.170.36
 Adult weight gain since age 21,c kg
  −130.5 to <5.41.001.001.001.001.00
  5.4 to <11.31.07 (0.92–1.25)1.23 (0.87–1.74)1.04 (0.76–1.41)0.99 (0.75–1.31)1.02 (0.77–1.34)
  11.3 to <17.61.17 (1.00–1.37)1.22 (0.87–1.71)1.34 (0.87–2.06)1.18 (0.88–1.56)0.97 (0.71–1.33)
  17.6 to <24.81.35 (1.13–1.61)1.56 (1.11–2.17)1.76 (0.96–3.26)1.11 (0.81–1.52)1.44 (1.01–2.04)
  25.2 to <90.01.56 (1.29–1.88)1.85 (1.30–2.61)1.51 (0.51–4.44)1.32 (0.94–1.83)1.60 (1.06–2.41)
  Ptrendb<0.01<0.010.080.050.08
Independent of individual-level + neighborhood-level factorsd
 BMI at baseline, kg/m2
  Underweight0.83 (0.57–1.21)0.99 (0.43–2.24)0.61 (0.31–1.2)1.17 (0.52–2.65)0.98 (0.49–1.95)
  Normal1.001.001.001.001.00
  Overweight1.01 (0.89–1.15)0.85 (0.69–1.04)1.30 (0.88–1.94)1.13 (0.91–1.41)0.94 (0.72–1.23)
  Obese0.99 (0.85–1.16)0.83 (0.65–1.05)1.02 (0.42–2.47)1.23 (0.96–1.59)0.84 (0.57–1.22)
  Ptrendb0.910.150.460.120.37
 Adult weight gain since age 21,c kg
  −130.5 to <5.41.001.001.001.001.00
  5.4 to <11.31.07 (0.92–1.25)1.24 (0.88–1.74)1.02 (0.75–1.4)1.00 (0.75–1.32)1.00 (0.76–1.32)
  11.3 to <17.61.17 (0.99–1.37)1.23 (0.88–1.72)1.32 (0.86–2.03)1.18 (0.88–1.56)0.97 (0.71–1.33)
  17.6 to <24.81.34 (1.13–1.60)1.55 (1.11–2.16)1.79 (0.96–3.32)1.10 (0.81–1.51)1.41 (0.99–2.00)
  25.2 to <90.01.56 (1.29–1.88)1.84 (1.30–2.60)1.59 (0.53–4.72)1.30 (0.94–1.82)1.58 (1.05–2.39)
  Ptrendb<0.01<0.010.080.050.09
  • NOTE: Values in bold represent P < 0.05.

  • aAdjusted for individual-level factors: age at entry, race/ethnicity for all women, family history of breast cancer, age at menarche, age at first live birth, number of children, hormone replacement therapy, ever had mammography, alcohol use, physical activity, and education, baseline BMI and adult weight change.

  • bTrend analysis excluding underweight and missing values. Trend variable was assigned ordinal value (i.e., 1, 2, 3) corresponding to categories.

  • cDifference between baseline weight and weight at age 21 categorized into quintiles based on study population distribution.

  • dAdjusted for individual-level factors with further adjustment for neighborhood SES and all neighborhood obesogenic factors (urban environment, unhealthy food, mixed-land development, parks).