Table 3 Hazard ratios (HR) and 95% confidence intervals (95% CI) of breast cancer death across hormone receptor subtypes by quartile of vitamin C intake among 3405 invasive breast cancer cases in the Swedish Mammography Cohort

From: Vitamin C intake and breast cancer mortality in a cohort of Swedish women

 

Quartile of vitamin C intake (mg d−1)

 
 

<42.9

42.9–65.5

65.6–92.4

⩾92.5

P trend a

P heterogeneity b

ER-positive/PR-positive

Breast cancer deaths

35

25

29

25

—

—

Person-years

3113

3426

3287

3410

—

0.73

Covariate-adjusted modelc

1.00

0.66 (0.39–1.11)

0.84 (0.51–1.38)

0.70 (0.42–1.17)

0.32

—

Covariate-adjusted model+clinical characteristicsd

1.00

0.75 (0.44–1.27)

0.85 (0.51–1.42)

0.80 (0.47–1.35)

0.52

—

ER-negative/PR-negative

Breast cancer deaths

18

23

16

15

—

—

Person-years

749

573

641

802

—

—

Covariate-adjusted modelc

1.00

1.36 (0.71–2.59)

0.96 (0.48–1.93)

0.67 (0.33–1.36)

0.14

—

Covariate-adjusted model+clinical characteristicsd

1.00

1.17 (0.60–2.29)

0.49 (0.23–1.06)

0.46 (0.22–0.96)

0.008

—

ER-positive

Breast cancer deaths

52

36

40

39

—

—

Person-years

3961

4527

4239

4286

 

0.65

Covariate-adjusted modelc

1.00

0.62 (0.41–0.96)

0.77 (0.51–1.17)

0.73 (0.48–1.12)

0.32

—

Covariate-adjusted model+clinical characteristicsd

1.00

0.73 (0.47–1.13)

0.82 (0.54–1.26)

0.88 (0.57–1.35)

0.72

—

ER-negative

Breast cancer deaths

32

29

20

21

—

—

Person-years

1113

866

1059

1039

—

—

Covariate-adjusted modelc

1.00

1.08 (0.65–1.82)

0.74 (0.42–1.32)

0.66 (0.37–1.15)

0.07

—

Covariate-adjusted model+clinical characteristicsd

1.00

0.97 (0.57–1.64)

0.42 (0.23–0.78)

0.50 (0.28–0.89)

0.004

—

PR-positive

Breast cancer deaths

49

31

33

31

—

—

Person-years

3491

3735

3715

3647

—

0.61

Covariate-adjusted modelc

1.00

0.61 (0.39–0.97)

0.70 (0.45–1.09)

0.64 (0.41–1.02)

0.11

—

Covariate-adjusted model+clinical characteristicsd

1.00

0.69 (0.43–1.10)

0.65 (0.41–1.03)

0.72 (0.45–1.15)

0.18

—

PR-negative

Breast cancer deaths

35

34

27

29

—

—

Person-years

1588

1659

1559

1652

—

—

Covariate-adjusted modelc

1.00

0.91 (0.56–1.48)

0.78 (0.47–1.31)

0.79 (0.48–1.31)

0.32

—

Covariate-adjusted model+clinical characteristicsd

1.00

0.99 (0.60–1.63)

0.64 (0.38–1.09)

0.76 (0.45–1.27)

0.15

—

  1. aDetermined using category medians.
  2. bP-value from likelihood ratio test comparing a model with the cross-product term between vitamin C and hormone receptor status to the model with main effects only.
  3. cCox proportional hazard model adjusted for age (continuous), energy intake (continuous), education level (primary, high school, university), marital status (single, married, divorced, widowed, living with partner), menopausal status at diagnosis, (premenopausal, postmenopausal, unknown), body mass index (<20, 20–24.9, 25–29.9, ⩾30 kg m−2), alcohol intake (non-drinker, <3.4, 3.4–9.9, ⩾10 g d−1) and calendar year of diagnosis (continuous).
  4. dCox proportional hazard model adjusted for the variables above plus disease stage (I, II, III/IV), grade (I, II, III), radiation treatment (yes/no), and chemotherapy and/or hormonal treatment (no chemotherapy or hormonal treatment, hormonal therapy and no chemotherapy, chemotherapy and no hormonal therapy, and hormonal therapy and chemotherapy).
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