Table 4.

Postdiagnosis vitamin supplement use in association with total mortality and breast cancer recurrence by use of radiotherapy, SBCSS (N = 4,877)a

Radiotherapy (n = 1,597)No radiotherapy (n = 3,280)
Vitamin useEvents/cohortHR (95% CI)PEvents/cohortHR (95% CI)P
Total mortality
Never postdiagnosis128/9901.00 (referent)169/2,1111.00 (referent)
Postdiagnosis use
 Any type79/6071.03 (0.77–1.38)0.8668/1,1690.75 (0.56–1.00)0.05
 Any antioxidantb63/5001.00 (0.73–1.37)0.9944/8800.65 (0.47–0.92)0.01
Used during radiotherapy
 Any type50/4180.94 (0.67–1.32)0.72
 Any antioxidantb40/3330.92 (0.63–1.33)0.66
Did not use during radiotherapy
 Any type29/1891.21 (0.80–1.84)0.36
 Any antioxidantb23/1671.14 (0.72–1.80)0.51
Breast cancer recurrence
Never postdiagnosis159/9901.00 (referent)198/2,1111.00 (referent)
Postdiagnosis use
 Any type96/6071.02 (0.78–1.33)0.9079/1,1690.72 (0.55–0.94)0.02
 Any antioxidantb78/5000.99 (0.74–1.31)0.9251/8800.63 (0.46–0.86)0.003
Used during radiotherapy
 Any type61/4180.93 (0.69–1.26)0.66
 Any antioxidantb48/3330.90 (0.64–1.26)0.53
Did not use during radiotherapy
 Any type35/1891.21 (0.83–1.76)0.33
 Any antioxidantb30/1671.16 (0.78–1.73)0.47
  • aHRs are adjusted for ER/PR status, TNM stage, chemotherapy, tamoxifen use, education, income, BMI, regular tea consumption, regular exercise participation (MET-hours per week), daily cruciferous vegetable intake, daily soy protein intake, and use of other types of vitamins (as appropriate). Adjusted HRs and their corresponding 95% CIs were derived from Cox proportional hazards regression models, using age as the time scale. P values for multiplicative interactions between radiotherapy and vitamin use were as follows: for use of any type of vitamin, P = 0.17 for total mortality and P = 0.14 for recurrence; for use of any antioxidant, P = 0.23 for total mortality and P = 0.17 for recurrence.

  • bIncludes women who used vitamin C, vitamin E, and/or multivitamins.