Skip to main content

Table 1 Distribution of demographic and established risk factors for breast cancer in cancer patients (cases) and control subjects, The Singapore Chinese Health Study, 1993 to 1998

From: Breast cancer risk assessment using genetic variants and risk factors in a Singapore Chinese population

 

Cases (n = 411)

Controls (n = 1,212)

P *

Demographic factors

Mean age, years (SD)

54.9 (7.6)

54.9 (7.5)

0.964

Education level, n (%)

  

0.003

None

104 (25.3)

399 (32.9)

Primary

186 (45.3)

518 (42.7)

Secondary or higher

121 (29.4)

295 (24.3)

Reproductive risk factors

Number of live births, n (%)

  

<0.001

Nulliparous

56 (13.6)

85 (7.0)

1-2

146 (35.5)

369 (30.4)

3-4

131 (31.9)

483 (39.9)

5 or more

78 (19.0)

275 (22.7)

Mean age at first live birth, years (SD)

25.6 (4.9)

25.0 (4.7)

0.022

Mean age at menarche, years (SD)

14.1 (1.7)

14.3 (1.8)

0.033

Mean age at menopause, years (SD)

49.7 (4.4)

49.2 (4.3)

0.141

Estrogen use, n (%)

  

0.042

Non-user

372 (90.5)

1,131 (93.3)

Ex-user

8 (1.9)

22 (1.8)

Current user

31 (7.5)

59 (4.9)

Other risk factors

Family history of breast cancer, n (%)

  

0.063

No

400 (97.3)

1,196 (98.7)

Yes

11 (2.7)

16 (1.3)

History of past biopsy, n (%)

  

0.252

No

401 (97.6)

1,193 (98.4)

Yes

10 (2.4)

19 (1.6)

Mean body mass index, kg/m2 (SD)

23.5 (3.4)

23.2 (3.2)

0.066

Marine n-3 omega fatty acids, g (SD)

0.90 (0.4)

0.90 (0.5)

0.299

Vegetable-fruit-soy intake, n (%)

  

0.969

0

79 (19.2)

241 (19.9)

1

99 (24.1)

307 (25.3)

2

130 (31.6)

332 (27.4)

3

103 (25.1)

332 (27.4)

Green tea intake in tertiles, n (%)

  

0.418

None

234 (56.9)

713 (58.8)

First

77 (18.7)

219 (18.1)

Second

43 (10.5)

134 (11.1)

Third

57 (13.9)

146 (12.0)

Mean isoflavanoids, mg (SD)

19.4 (20.4)

19.8 (17.3)

0.700

Sleep duration, hours per day (SD)

7.0 (1.1)

7.0 (1.1)

0.685

Genetic risk score in quartiles, n (%)

   

First (32.4 - 43.6)

80 (19.5)

326 (26.9)

<0.001

Second (43.6 - 47.1)

96 (23.4)

310 (25.6)

 

Third (47.1 - 50.6)

109 (26.5)

296 (24.4)

 

Fourth (50.6 - 65.8)

126 (30.7)

280 (23.1)

  1. *Two-sided P values were derived from chi-squared test for categorical variables and t test for continuous variables; the Mantel-Haenszel chi-squared test for trend with one degree of freedom for categorical variables with more than two levels. SD, standard deviation.