Table 1

Characteristics of women with breast cancer and their matched controls

Variablea
Cases of cancer (n = 252)
Controls (n = 252)

Hypothesised risk factors


     Absolute breast volume FA (ml; median (IQR))
63.17 (88.54)
52.99 (68.38)
     Relative breast volume FA (%; median (IQR))
2.70 (3.63)
2.49 (2.91)



Other potential risk factors/confounders


     BMI (n = 503; mean (SD))
23.8 (3.11)
23.9 (3.22)
     Height (cm; mean (SD))
161.7 (6.10)
159.7 (5.88)
     Age at menarche (years; n = 503; mean (SD))
13.0 (1.61)
13.6 (1.68)
     Age at 1st pregnancy (years; n = 400; mean (SD))
25.4 (4.19)
23.9 (4.31)
     Number of pregnancies (n = 503; median (IQR))
2 (2)
2 (2)
     Family history
68 (27%)
32 (13%)
     Mean breast volume (ml; median (IQR))
569 (388)
582 (370)
     Parenchyma type: right breast


          N1
21 (8%)
54 (21%)
          P1
42 (17%)
33 (13%)
          P2
65 (26%)
40 (16%)
          DY
124 (49%)
125 (50%)
     Parenchyma type: left breast


          N1
21 (8%)
55 (22%)
          P1
42 (17%)
33 (13%)
          P2
65 (26%)
43 (17%)
          DY
124 (49%)
121 (48%)
     Menopausal status (n = 482)


          Pre
99 (41%)
76 (32%)
          Peri
44 (18%)
49 (20%)
          Post
100 (41%)
114 (48%)
     Age at menopause (years; n = 212; median (IQR))
50 (4)
47 (6)

Values are numbers (percentages) unless stated otherwise. aIncomplete total is indicated in brackets where there are missing data. Absolute breast volume fluctuating asymmetry (FA) = unsigned values (|L - R|) of breast volume. Relative breast volume FA = 100 × |L - R| breast volume/[|L + R| breast volume] 0.5. BMI, body mass index; IQR, inter-quartile range; SD, standard deviation.

Scutt et al. Breast Cancer Research 2006 8:R14   doi:10.1186/bcr1388