Table 1

Characteristics and risk factors for postmenopausal breast cancer in cases and matched controls in the study population
Characteristics
 Cases (na = 1,408)
 Controls (na+ = 2,612)
 Pb

n
 %
 n
 %
Age at diagnosis/recruitment (years)



0.87
     50 to 54
 104
 7.4
 191
 7.3
     55 to 59
 301
 21.4
 528
 20.2
     60 to 64
 447
 31.7
 859
 32.9
     65 to 69
 380
 27.0
 720
 27.6
     ≥70
 176
 12.5
 314
 12.0
BMI (kg/m2)



0.68
     < 22.5
 554
 39.4
 1,043
 39.9
     22.5 to < 25
 473
 33.6
 829
 31.8
     25 to < 30
 323
 22.9
 624
 23.9
     ≥30
 58
 4.1
 114
 4.4
Educational level



0.07
     Low
 912
 64.8
 1,761
 67.4
     Middle
 305
 21.6
 559
 21.4
     High
 191
 13.6
 292
 11.2
Age at menopause (years)



< 0.01
     < 47
 146
 10.4
 396
 15.2
     47 to 51
 407
 28.9
 748
 28.6
     52 to 55
 248
 17.6
 402
 15.4
     ≥56
 63
 4.5
 115
 4.4
     Unknown
 544
 38.6
 951
 36.4
First degree family history of breast cancer



< 0.01
     No
 1,113
 79.1
 2,164
 82.8
     Yes
 234
 16.6
 329
 12.6
     Unknown
 61
 4.3
 119
 4.6
Benign breast disease



< 0.01
     No
 860
 61.3
 1,833
 70.5
     Yes
 544
 38.7
 766
 29.5
Number of pregnancies (≥ 28th week)



< 0.01
     0
 200
 14.2
 294
 11.3
     1
 383
 27.2
 635
 24.3
     2
 518
 36.8
 1,031
 39.5
     ≥3
 307
 21.8
 652
 24.9
Age at menarche (years)



0.02
     < 12
 125
 8.9
 221
 8.5
     12 to 14
 950
 67.5
 1,658
 63.7
     ≥15
 333
 23.6
 725
 27.8
Ever breastfeeding



< 0.01
     No
 555
 39.4
 868
 33.2
     Yes
 853
 60.6
 1,744
 66.8
Number of mammograms in total



< 0.01
     0
 195
 13.8
 334
 12.8
     1 to 4
 598
 42.5
 1,370
 52.5
     5 to 9
 343
 24.4
 599
 22.9
     ≥10
 254
 18.0
 288
 11.0
     Unknown number
 18
 1.3
 21
 0.8
Use of hormone therapy



< 0.01
     Never
 528
 37.9
 1,113
 43.1
     Past
 293
 21.0
 672
 26.0
     Current (≤ 6 months)
 572
 41.1
 798
 30.9
Hormonal receptor status of the tumorc




     ER-positive
 994
 76.3


     ER-negative
 308
 23.7


     PR-positive
 848
 65.2


     PR-negative
 453
 34.8


Time of blood collectiond



0.99
     January to March
 317
 22.8
 311
 22.8
     April to June
 292
 21.0
 286
 21.0
     July to September
 402
 28.9
 392
 28.7
     October to December
 380
 27.3
 376
 27.5

aNumbers do not always add up to total numbers because of missing values. bχ2 test for differences between cases and controls. cData on estrogen receptor (ER) and progesterone receptor (PR) status was available for 1,302 and 1,301 invasive tumour cases (in situ tumours excluded), respectively. dData on serum 25-hydroxyvitamin D status were available for 1,391 cases and 1,365 controls. BMI, body mass index.

Abbas et al. Breast Cancer Research 2008 10:R31   doi:10.1186/bcr1994