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Table 6 Histological grade by parity and age at first birth.

From: Histological type and grade of breast cancer tumors by parity, age at birth, and time since birth: a register-based study in Norway

 

Total no.

Grade 3-4 (%)

Parity

  

0

1261

38.2

≥ 1

8283

36.2

P-value a

 

0.17

Parous women:

  

1

1446

34.8

2

3767

35.7

3

2100

36.4

≥ 4

970

40.1**

P-value a

 

0.045

OR, unadjustedb

 

1.1**

OR, adjustedb , c,d

 

1.1**

Age at first birth (yr) d

  

<20 yr

1008

37.7

20 - 24 yr

3672

37.7

25 - 29 yr

2491

35.0

≥ 30 yr

1110

32.7(**)

P-value a

 

0.0076

OR, unadjustedb

 

0.92**

OR, adjustedb,c

 

0.98

  1. Histological grade of breast cancer tumors by parity and maternal age at first birth
  2. a 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
  3. b OR (grade 3-4 vs. grade 1-2) for linear trend through ordered categories of exposure variable, with significant test for trend (p < 0.05) marked with **
  4. c Adjusted for age at diagnosis and age at first birth/parity
  5. d Two cases excluded due to missing value for age at first birth
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BMC Cancer

ISSN: 1471-2407

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