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Table 1 Characteristics of controls and breast cancer cases.

From: Analysis of polymorphisms in the circadian-related genes and breast cancer risk in Norwegian nurses working night shifts

Parameter

Cases (n = 563)

Controls (n = 619)

Pvalue

Age (yr)a

  

0.51b

   Mean (SD)

52.40 (7.88)

52.37 (8.18)

 

   Median

50

55

 

   Min/max

34/70

34/70

 

Selection period

   

   1996 to 1999/2000 to 2007 (n)

195/368

221/398

0.72c

Breast cancer in first-degree familyd (n)

557

615

 

   Yes/no

104/453

54/561

<0.001c

Hormone therapy in past 2 yre (n)

552

605

 

   Yes/no

127/425

121/484

0.22c

Alcohol usef

n = 563

n = 619

 

   Yes/no

43/520

37/582

0.26c

Children (n)

563

619

 

   0/≥1

77/486

81/538

0.80c

  1. aAge at selection for controls and age at diagnosis for cases. bDerived from Mann-Whitney U-test for two independent samples (two-sided) assuming the medians are the same across cases and controls. cPearson's χ2 test (two-sided). d Cancer in sister or mother. eHormone therapy among postmenopausal women only. fAlcohol consumption at least twice weekly.