Table 4.
Effect modification of an association a between breast cancer and exposure variables by age and mammographic density in 13,572 women
| Breast cancer N (%) | Birth weight HR (95% CI) | BMI at age 13 HR (95% CI) | Height at age 13 HR (95% CI) | |
|---|---|---|---|---|
| Age at BC diagnoses (years) |
|
|
|
|
| 50-59 years |
193 (27.0) |
1.01 (0.75-1.36) |
1.03 (0.88-1.22) |
1.06 (0.92-1.23) |
| 60+ years |
523 (73.0) |
0.82 (0.66-1.02) |
1.00 (0.90-1.11) |
1.10 (1.00-1.20) |
| P value for interaction |
|
0.31 |
0.81 |
0.69 |
| Mammographic density |
|
|
|
|
| Mixed/dense breasts |
541 (75.5) |
0.88 (0.72-1.07) |
1.02 (0.92-1.14) |
1.13 (1.03-1.23) |
| Fatty breasts |
175 (24.4) |
0.92 (0.62-1.36) |
1.00 (0.81-1.17) |
0.97 (0.83-1.13) |
| P value for interaction |
|
0.85 |
0.70 |
0.08 |
| Total | 716 | 0.89 (0.75-1.06) | 1.01 (0.93-1.11) | 1.09 (1.01-1.17) |
CI, confidence interval; HR, hazard ratio; aAdjusted for age (underlying time scale) and mammographic density, and stratified by birth cohort (1930 to 1934, 1935 to 1939, 1940 to 1944, 1945 to 1949).