Table 3.
Multivariable Logistic Regressions on Risk Factors for Three Types of Breast Cancers among Parous Premenopausal Women, Nigeria (N=1,446), 1998-2011a
| PABC | Non-PABC | |||
|---|---|---|---|---|
|
|
||||
| ≤2 years postpartum |
3-5 years postpartum |
>5 years postpartum or nulliparous |
P for heterogeneity |
|
|
|
||||
| Sample Size: Cases | N=152 | N=145 | N=421 | |
| Controls | N=282 | N=188 | N=525 | |
| Odds ratio: Case vs. Control (95% confidence interval) | ||||
| Parity | ||||
| 1-2 | 1.0 (ref.) | 1.0 (ref.) | 1.0 (ref.) | 0.097 |
| 3-5 | 1.79 (0.80-4.00) | 1.20 (0.44-3.28) | 0.86 (0.46-1.60) | |
| ≥6 | 2.12 (0.50-9.04) | 1.87 (0.39-9.00) | 0.66 (0.26-1.66) | |
| P for trend | 0.2 | 0.4 | 0.4 | |
| Per birth | 1.20 (0.92-1.57) | 1.13 (0.83-1.55) | 0.92 (0.76-1.11) | |
|
| ||||
| Age at first live birth (years) | ||||
| <25 | 1.0 (ref.) | 1.0 (ref.) | 1.0 (ref.) | 0.6 |
| 25-29 | 1.15 (0.59-2.20) | 1.05 (0.53-2.05) | 0.83 (0.53-1.29) | |
| ≥30 | 1.06 (0.42-2.69) | 1.18 (0.40-3.51) | 0.79 (0.36-1.73) | |
| P for trend | 0.9 | 0.8 | 0.4 | |
|
| ||||
| Lifetime duration of breastfeeding (months) | ||||
| ≤24 | 1.0 (ref.) | 1.0 (ref.) | 1.0 (ref.) | 0.8 |
| 25-48 | 1.12 (0.55-2.29) | 0.92 (0.37-2.31) | 0.82 (0.46-1.46) | |
| 49-72 | 0.56 (0.21-1.50) | 1.05 (0.37-3.00) | 0.75 (0.39-1.43) | |
| 73-96 | 0.54 (0.13-2.25) | 1.92 (0.48-7.75) | 0.99 (0.42-2.35) | |
| >96 | 1.03 (0.16-6.85) | 1.37 (0.20-9.42) | 0.97 (0.33-2.82) | |
| P for trend | 0.4 | 0.5 | 0.9 | |
|
| ||||
| Mean duration of breastfeeding per live birth (months) | ||||
| <12 | 1.0 (ref.) | 1.0 (ref.) | 1.0 (ref.) | 0.3 |
| ≥12 | 0.75 (0.44-1.30) | 0.90 (0.47-1.73) | 1.01 (0.70-1.45) | |
|
| ||||
| Number of abortion | ||||
| 0 | 1.0 (ref.) | 1.0 (ref.) | 1.0 (ref.) | 0.6 |
| 1 | 1.14 (0.59-2.21) | 0.96 (0.44-2.09) | 0.92 (0.57-1.49) | |
| ≥2 | 0.95 (0.45-2.04) | 0.55 (0.25-1.22) | 0.84 (0.52-1.36) | |
| P for trend | 0.99 | 0.2 | 0.5 | |
PABC, pregnancy-associated breast cancer
a
Independent variables include parity, age at first live birth, breastfeeding duration (lifetime or per live birth, in separate models), number of abortion, age in 3-year category, ethnicity, education, family history of breast cancer, previous benign breast diseases, hormonal contraceptive use, alcohol drinking, height, and body mass index.