Table 1 Description of the Singapore Breast Cancer Screening Project (SBCSP) study (n = 24,353) and the associations with different breast size (bust line in cm or total breast area on mammogram in cm2) or breast component (dense area or nondense area in cm2) measurements from unadjusted linear regression models. Beta and standard errors for breast area and dense area correspond to analyses performed on the square-root transformed scale. *Denotes back-transformed values for ease of interpretation.
n (%) | Bust line | Breast area | Nondense | Dense area | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Beta (SE) | p-value | Beta* | Beta (SE) | p-value | Beta (SE) | p-value | Beta* | Beta (SE) | p-value | ||
Age at entry | |||||||||||
<55 | 7377 (30.3) | Referent | Referent | Referent | Referent | ||||||
55–59 | 9034 (37.1) | 0.29 (0.13) | 0.022 | 2.61 | 0.13 (0.02) | <0.001 | 7.32 (0.37) | <0.001 | −4.61 | −0.50 (0.02) | <0.001 |
≥60 | 7942 (32.6) | 1.13 (0.13) | <0.001 | 6.03 | 0.30 (0.02) | <0.001 | 15.41 (0.38) | <0.001 | −9.23 | −1.06 (0.02) | <0.001 |
P-trend | <0.001 | <0.001 | <0.001 | <0.001 | |||||||
Ethnicity | |||||||||||
Chinese | 20719 (85.1) | Referent | Referent | Referent | Referent | ||||||
Malay | 1313 (5.4) | 3.70 (0.23) | <0.001 | 18.82 | 0.91 (0.03) | <0.001 | 24.30 (0.66) | <0.001 | −5.23 | −0.64 (0.04) | <0.001 |
Indian | 1132 (4.6) | 2.63 (0.25) | <0.001 | 18.56 | 0.89 (0.03) | <0.001 | 19.59 (0.70) | <0.001 | −0.78 | −0.09 (0.04) | 0.033 |
Other | 1189 (4.9) | 3.07 (0.24) | <0.001 | 18.04 | 0.87 (0.03) | <0.001 | 20.63 (0.69) | <0.001 | −2.51 | −0.29 (0.04) | <0.001 |
Marital status | |||||||||||
Married | 19484 (80.0) | Referent | Referent | Referent | Referent | ||||||
Divorced | 3807 (15.6) | −4.07 (0.26) | <0.001 | −7.62 | −0.39 (0.03) | <0.001 | −15.08 (0.76) | <0.001 | 7.79 | 0.81 (0.04) | <0.001 |
Single | 1062 (4.4) | 0.54 (0.14) | <0.001 | 2.50 | 0.12 (0.02) | <0.001 | 5.08 (0.43) | <0.001 | −2.52 | −0.30 (0.02) | <0.001 |
Occupation | |||||||||||
Housewife | 15379 (63.2) | Referent | Referent | Referent | Referent | ||||||
Employed | 7918 (32.5) | −1.66 (0.11) | <0.001 | −5.49 | −0.27 (0.01) | <0.001 | −9.65 (0.33) | <0.001 | 4.05 | 0.46 (0.02) | <0.001 |
Unemployed | 91 (0.4) | −3.42 (0.85) | <0.001 | −4.92 | −0.24 (0.10) | 0.019 | −10.12 (2.51) | <0.001 | 4.94 | 0.55 (0.14) | <0.001 |
Retired | 965 (3.9) | −2.91 (0.27) | <0.001 | −4.87 | −0.24 (0.03) | <0.001 | −9.04 (0.79) | <0.001 | 4.07 | 0.46 (0.05) | <0.001 |
Body mass index | |||||||||||
≥30 | 2151 (8.8) | 7.91 (0.13) | <0.001 | 16.96 | 0.78 (0.02) | <0.001 | 19.25 (0.49) | <0.001 | −1.96 | −0.24 (0.03) | <0.001 |
25–29 | 8158 (33.5) | Referent | Referent | Referent | Referent | ||||||
20–24 | 11425 (46.9) | −7.52 (0.07) | <0.001 | −13.78 | −0.68 (0.01) | <0.001 | −16.55 (0.29) | <0.001 | 2.61 | 0.30 (0.02) | <0.001 |
<20 | 2619 (10.8) | −16.35 (0.12) | <0.001 | −27.53 | −1.41 (0.02) | <0.001 | −33.91 (0.45) | <0.001 | 6.36 | 0.70 (0.03) | <0.001 |
P-trend | <0.001 | <0.001 | <0.001 | <0.001 | |||||||
Number of children | |||||||||||
0 | 1936 (7.9) | Referent | Referent | Referent | Referent | ||||||
1 | 1344 (5.5) | 0.99 (0.29) | <0.001 | 2.61 | 0.13 (0.04) | <0.001 | 5.00 (0.84) | <0.001 | −2.53 | −0.25 (0.05) | <0.001 |
2 | 4011 (16.5) | 1.28 (0.22) | <0.001 | 2.00 | 0.10 (0.03) | <0.001 | 5.52 (0.66) | <0.001 | −3.83 | −0.38 (0.04) | <0.001 |
≥3 | 17062 (70.1) | 3.61 (0.19) | <0.001 | 6.08 | 0.30 (0.02) | <0.001 | 15.88 (0.57) | <0.001 | −10.05 | −1.08 (0.03) | <0.001 |
P-trend | <0.001 | <0.001 | <0.001 | <0.001 | |||||||
Age at first birth (in subset of women with children) | |||||||||||
<22 | 8296 (37) | Referent | Referent | Referent | Referent | ||||||
22–26 | 8018 (35.8) | −1.99 (0.12) | <0.001 | −6.24 | −0.31 (0.02) | <0.001 | −9.88 (0.36) | <0.001 | 3.38 | 0.41 (0.02) | <0.001 |
≥27 | 6103 (27.2) | −3.32 (0.13) | <0.001 | −9.15 | −0.45 (0.02) | <0.001 | −15.23 (0.39) | <0.001 | 5.95 | 0.69 (0.02) | <0.001 |
Ptrend | <0.001 | <0.001 | <0.001 | <0.001 | |||||||
Breastfeed (in subset of women with children) | |||||||||||
Yes | 15459 (63.5) | Referent | Referent | Referent | Referent | ||||||
No | 6958 (28.6) | −1.75 (0.12) | <0.001 | −4.69 | −0.23 (0.01) | <0.001 | −8.13 (0.34) | <0.001 | 3.37 | 0.39 (0.02) | <0.001 |
Menopausal status | |||||||||||
Pre-menopausal | 2574 (10.6) | Referent | Referent | Referent | Referent | ||||||
Post-menopausal | 21779 (89.4) | 0.30 (0.17) | 0.076 | 4.22 | 0.21 (0.02) | <0.001 | 13.41 (0.50) | <0.001 | −9.14 | −0.96 (0.03) | <0.001 |
Oral contraceptives | |||||||||||
No | 15059 (61.8) | Referent | Referent | Referent | Referent | ||||||
Yes | 9294 (38.2) | 0.46 (0.11) | <0.001 | −0.44 | −0.02 (0.01) | 0.094 | −0.05 (0.32) | 0.869 | −0.42 | −0.05 (0.02) | 0.009 |
Hormone replacement therapy | |||||||||||
No | 21052 (86.4) | Referent | Referent | Referent | Referent | ||||||
Yes | 3301 (13.6) | −1.73 (0.15) | <0.001 | −4.41 | −0.22 (0.02) | <0.001 | −9.99 (0.45) | <0.001 | 5.54 | 0.60 (0.03) | <0.001 |
Family history of breast cancer | |||||||||||
No | 23729 (97.4) | Referent | Referent | Referent | Referent | ||||||
Yes | 624 (2.6) | −0.74 (0.33) | 0.025 | −0.72 | −0.04 (0.04) | 0.374 | −4.45 (0.99) | <0.001 | 3.91 | 0.43 (0.06) | <0.001 |
