| | First birtha
| Last birthb
|
|---|
| | Total no. | Grade 3-4 (%) | Total no. | Grade 3-4 (%) |
|---|
Years since birth
| | | | |
DP, <2 | 31 | 54.8 | 132 | 62.1** |
2 - 5 | 133 | 52.6 | 352 | 52.3** |
6 - 9 | 239 | 49.8 | 467 | 46.7 |
10 - 14 | 505 | 48.1 | 728 | 44.8 |
15 - 19 | 754 | 46.4 | 753 | 43.0 |
≥ 20 | 1547 | 42.5(*)
| 665 | 40.2(*)
|
P-valuec
| | 0.026 | | <0.001 |
OR, unadjustedd
| | 0.90** | | 0.88** |
OR, adjustedd,e
| | 1.00 | | 0.94 |
OR, adjustedd,f
| | 0.98 | | 0.98 |
- Histological grade of breast cancer tumors by time interval since a childbirth
-
a Results based on 3209 parous women diagnosed before age 50 years
-
b Results based on 3097 parous women diagnosed before age 50 years, with singleton births only (1st to 5th birth)
-
c Chi-square test for difference in proportions between groups, with significant cell-specific contributions to the chi-square statistic at 5% level marked with ** (Χ ≥ 1.96), and significant contributions at 10% level marked with * (Χ ≥ 1.64); in brackets if the observed number is lower than expected by chance
-
d OR (grade 3-4 vs. grade 1-2) for linear trend through ordered categories of exposure variable, significant trend (p < 0.05) marked with **
-
e Adjusted for age at diagnosis
-
f Adjusted for age at diagnosis and parity
