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Table 1 Demographic characteristics in cases and controls (n = 1030)

From: Perfluoroalkyl substances (PFASs) as risk factors for breast cancer: a case–control study in Chinese population

Characteristics

Case (n = 373)

Control (n = 657)

P-value

Median (IQR)/N (%)

Median (IQR)/N (%)

Age at baseline (years)

50.6 (44.4, 59.2)

53.0 (50.0, 57.0)

0.043

BMI (kg/m2)

24.4 (22.3, 26.5)

24.0 (22.1, 26.3)

0.150

Smoking history

  

0.043

 Nonsmoker

343 (92.0%)

603 (95.1%)

 

 Current or Former smoker

30 (8.0%)

31 (4.9%)

 

Alcohol consumption

  

0.072

 Nondrinker

368 (98.7%)

611 (96.8%)

 

 Current or Former drinker

5 (1.3%)

20 (3.2%)

 

Age at menarche (years)

  

< 0.001

 < 13

28 (7.6%)

101 (15.5%)

 

 ≥ 13

342 (92.4%)

551 (84.5%)

 

Age at menopause (years)

  

< 0.001

 Pre/Peri-menopausal

187 (51.2%)

184 (29.0%)

 

 < 51

109 (29.9%)

291 (46.0%)

 

 ≥ 51

69 (18.9%)

158 (25.0%)

 

Parity

  

< 0.001

 < 2

246 (66.1%)

553 (85.3%)

 

 ≥ 2

126 (33.9%)

95 (14.7%)

 

Breastfeeding duration (months)

  

< 0.001

 < 13

139 (39.7%)

422 (66.8%)

 

 ≥ 13

211 (60.3%)

210 (33.2%)

 

Use of estrogen or estrogen replacement therapy

  

0.598

 No

355 (95.9%)

514 (96.6%)

 

 Yes

15 (4.1%)

18 (3.4%)

 

Family history of breast cancer

  

0.015

 No

349 (93.8%)

615 (97.0%)

 

 Yes

23 (6.2%)

19 (3.0%)

 

Education (years)

  

0.200

 < 13

284 (76.1%)

518 (79.6%)

 

 ≥ 13

89 (23.9%)

133 (20.4%)

 

Monthly household income per capita (RMB/month)

  

0.062

 < 1000

39 (11.2%)

50 (7.7%)

 

 1000–1999

114 (32.9%)

187 (28.9%)

 

 2000–2999

117 (33.7%)

228 (35.3%)

 

 ≥ 3000

77 (22.2%)

181 (28.0%)

 

Red meat consumption

  

0.372

 Rare

174 (46.6%)

324 (49.5%)

 

 Occasional

148 (39.7%)

235 (35.9%)

 

 Often

51 (13.7%)

95 (14.5%)

 

Pickled food consumption

  

< 0.001

 Rare

222 (59.5%)

597 (91.8%)

 

 Occasional

98 (26.3%)

41 (6.3%)

 

 Often

53 (14.2%)

12 (1.8%)

 

Fried food consumption

  

0.169

 Rare

309 (82.8%)

564 (86.1%)

 

 Occasional

50 (13.4%)

78 (11.9%)

 

 Often

14 (3.8%)

13 (2.0%)

 

Smoked food consumption

  

0.103

 Rare

352 (94.9%)

610 (96.7%)

 

 Occasional

15 (4.0%)

20 (3.2%)

 

 Often

4 (1.1%)

1 (0.1%)

 

Barbequed food consumption

  

0.001

 Rare

345 (92.5%)

616 (97.5%)

 

 Occasional

21 (5.6%)

14 (2.2%)

 

 Often

7 (1.9%)

2 (0.3%)

 
  1. Continuous variables were presented as median (25th, 75th); and categorical variables were presented as number (percentage)
  2. Abbreviations: BMI Body mass index, IQR Interquartile range