Table 3.
Case-case analyses of established breast cancer risk factors with E-cadherin tumor tissue expression (low/high) among ER-negative tumors.
| Risk Factor | Estrogen Receptor Negative Tumors | |||
|---|---|---|---|---|
| No. of Cases | Cases, N (E-cadherin Low/High) |
OR (95% CI)a | P-hetb | |
| Family history of breast cancer | 9 | |||
| Absent | 173/660 | 1.0 (Ref) | ||
| Present | 60/207 | 1.32 (0.88–1.97) | 0.18 | |
| Age at menarche | 8 | |||
| ≤12 years | 69/225 | 1.27 (0.87–1.85) | ||
| 13 years | 43/182 | 0.94 (0.62–1.44) | ||
| ≥14 years | 81/291 | 1.0 (Ref) | 0.34 | |
| Parity | 9 | |||
| Nulliparous | 27/108 | 0.82 (0.51–1.33) | ||
| 1 | 48/190 | 0.82 (0.56–1.21) | ||
| ≥2 | 126/441 | 1.0 (Ref) | 0.52 | |
| Age at first birth (among parous women) | 6 | |||
| <20 years | 18/59 | 1.0 (Ref) | ||
| 20–24 years | 64/257 | 0.84 (0.46–1.54) | ||
| 25–29 years | 53/144 | 1.26 (0.67–2.35) | ||
| ≥30 years | 22/86 | 0.93 (0.45–1.93) | 0.32 | |
| Oral contraceptive use (among women at age ≤50 yearsc) | 5 | |||
| Never | 23/125 | 1.0 (Ref) | ||
| Ever | 37/132 | 1.97 (0.96–4.06) | 0.06 | |
| Menopausal hormone (MH) use (among women at age >50 yearsc) | 6 | |||
| Never | 63/207 | 1.0 (Ref) | ||
| Ever | 48/154 | 1.25 (0.78–2.00) | 0.35 | |
| Type of ever MH use (among women at age >50 yearsc) | 6 | |||
| Never | 63/207 | 1.0 (Ref) | ||
| Estrogen only | 4/27 | 0.46 (0.14–1.45) | ||
| Estrogen + Progestin | 14/32 | 1.67 (0.80–3.49) | ||
| Unknown | 30/95 | 1.38 (0.78–2.46) | 0.16 | |
aLogistic regression analyses were used to estimate the associations between E-cadherin tumor tissue expression and established breast cancer risk factors using E-cadherin expression levels (low vs. high) as the outcome variable and the risk factors as the independent variable, adjusted for age (10-year categories) and study site.
bP-values for heterogeneity by E-cadherin subtype were estimated using global F test, adjusted for age and study site.
cAge ≤ 50 years was used as a proxy for premenopausal status and age > 50 years was used as a proxy for postmenopausal status.
Abbreviations: OR = odds ratio, CI = confidence interval, ER = estrogen receptor
Note: For each variable, the category that has been shown to be associated with the lowest overall breast cancer risk in the literature was selected as the reference category. The case-case OR may be interpreted as the ratio of case-control ORs for E-cadherin low tumors (vs. controls) and E-cadherin high tumors (vs. controls). The case-case OR > 1 may suggest that the risk factor association is more strongly associated with E-cadherin low tumors than with E-cadherin high tumors (ORE-cadherin low vs. control > ORE-cadherin high vs. control).