Table 3.

Association between quintiles of plasma α-tocopherol and prostate cancer risk stratified by Gleason grade, smoking status, follow-up time, and by trial supplementation, SELECT case–cohort study

Plasma α-tocopherol quintiles
12345Ptrend
Histologic grade
 Gleason 26
  Cases/subcohort, na171/681201/656209/629209/616203/624
  Overall HRb (95% CI)1.001.14 (0.89–1.45)1.13 (0.88–1.44)1.12 (0.88–1.44)1.06 (0.82–1.36)0.80
  Placebo1.001.04 (0.64–1.69)1.16 (0.71–1.89)0.94 (0.57–1.53)1.04 (0.63–1.73)0.93
  α-Tocopherol only1.000.83 (0.52–1.32)0.95 (0.60–1.52)0.82 (0.51–1.32)0.56 (0.34–0.93)0.04
  Selenomethionine only1.001.12 (0.69–1.81)1.33 (0.82–2.16)1.22 (0.75–1.99)1.10 (0.67–1.79)0.65
  α-Tocopherol and selenomethionine1.001.72 (1.04–2.85)0.94 (0.56–1.58)1.62 (0.98–2.68)1.75 (1.06–2.91)0.08
  Any selenomethionine1.001.37 (0.96–1.94)1.15 (0.81–1.63)1.41 (0.99–2.00)1.39 (0.98–1.98)0.10
  Any α-tocopherol1.001.17 (0.83–1.64)0.96 (0.68–1.35)1.12 (0.80–1.59)0.98 (0.69–1.40)0.82
 Gleason 710
  Cases/subcohort, na72/68189/656103/629117/616117/624
  Overall HRb (95% CI)1.001.15 (0.81–1.64)1.45 (1.03–2.04)1.58 (1.13–2.21)1.59 (1.13–2.24)0.001
  Placebo1.001.64 (0.75–3.60)2.50 (1.18–5.30)1.81 (0.85–3.86)1.73 (0.78–3.82)0.28
  α-Tocopherol only1.000.89 (0.47–1.69)0.89 (0.47–1.68)1.24 (0.67–2.32)0.93 (0.48–1.80)0.77
  Selenomethionine only1.001.13 (0.52–2.45)2.10 (1.01–4.36)2.41 (1.19–4.88)2.58 (1.27–5.26)0.001
  α-Tocopherol and selenomethionine1.001.27 (0.65–2.50)1.24 (0.64–2.41)1.51 (0.78–2.92)1.75 (0.92–3.32)0.08
  Any selenomethionine1.001.21 (0.73–2.01)1.62 (1.00–2.64)1.92 (1.18–3.10)2.12 (1.32–3.40)0.0002
  Any α-tocopherol1.001.08 (0.68–1.71)1.06 (0.67–1.68)1.35 (0.86–2.13)1.29 (0.81–2.04)0.17
Smoking status
 Never smokers
  Cases/subcohort, na146/289163/276168/268172/264177/259
  Overall HRb (95% CI)1.000.96 (0.72–1.30)1.05 (0.78–1.41)1.03 (0.76–1.40)1.10 (0.81–1.49)0.44
  Placebo1.001.00 (0.54–1.85)1.21 (0.65–2.24)0.81 (0.42–1.57)0.99 (0.51–1.92)0.78
  α-Tocopherol only1.000.66 (0.37–1.19)0.66 (0.37–1.19)0.67 (0.37–1.21)0.58 (0.32–1.05)0.11
  Selenomethionine only1.001.29 (0.71–2.35)1.64 (0.90–2.97)1.47 (0.80–2.69)1.84 (1.00–3.39)0.05
  α-Tocopherol and selenomethionine1.001.19 (0.65–2.18)0.89 (0.49–1.63)1.08 (0.58–2.01)1.66 (0.90–3.06)0.18
  Any selenomethionine1.001.19 (0.78–1.82)1.16 (0.76–1.77)1.35 (0.88–2.08)1.70 (1.11–2.61)0.01
  Any α-tocopherol1.000.90 (0.59–1.36)0.79 (0.52–1.20)0.84 (0.55–1.29)0.91 (0.59–1.39)0.62
 Current and former smokers
  Cases/subcohort, na146/402187/369193/363202/352186/364
  Overall HRb (95% CI)1.001.40 (1.06–1.84)1.35 (1.03–1.78)1.43 (1.09–1.88)1.26 (0.95–1.67)0.18
  Placebo1.001.18 (0.67–2.10)1.18 (0.67–2.06)1.14 (0.65–1.99)1.01 (0.57–1.80)0.93
  α-Tocopherol only1.001.05 (0.62–1.77)1.27 (0.75–2.16)0.99 (0.58–1.67)0.85 (0.48–1.50)0.51
  Selenomethionine only1.001.17 (0.63–2.16)1.48 (0.82–2.66)1.64 (0.91–2.93)1.52 (0.84–2.75)0.09
  α-Tocopherol and selenomethionine1.001.68 (0.98–2.89)1.11 (0.64–1.92)1.86 (1.09–3.16)1.53 (0.88–2.64)0.15
  Any selenomethionine1.001.33 (0.87–2.03)1.47 (0.98–2.21)1.60 (1.06–2.41)1.44 (0.95–2.20)0.06
  Any α-tocopherol1.001.33 (0.92–1.93)1.16 (0.80–1.70)1.32 (0.90–1.92)1.11 (0.75–1.63)0.72
Follow-up time to diagnosis
 <3 years
  Cases/subcohort, na113/681124/656158/629149/616154/624
  Overall HRb (95% CI)1.001.08 (0.80–1.45)1.41 (1.06–1.87)1.29 (0.97–1.72)1.30 (0.98–1.74)0.03
  Placebo1.000.96 (0.55–1.69)1.27 (0.74–2.19)0.74 (0.41–1.34)0.88 (0.48–1.59)0.42
  α-Tocopherol only1.000.89 (0.51–1.55)1.05 (0.61–1.80)1.22 (0.71–2.08)0.73 (0.41–1.27)0.61
  Selenomethionine only1.001.14 (0.59–2.19)2.40 (1.31–4.37)1.94 (1.06–3.54)2.09 (1.15–3.79)0.003
  α-Tocopherol and selenomethionine1.001.31 (0.73–2.36)1.24 (0.69–2.25)1.67 (0.93–2.99)2.04 (1.16–3.61)0.01
  Any selenomethionine1.001.27 (0.82–1.96)1.78 (1.17–2.70)1.78 (1.17–2.71)2.08 (1.38–3.12)0.0001
  Any α-tocopherol1.001.09 (0.73–1.64)1.14 (0.76–1.70)1.39 (0.93–2.06)1.22 (0.81–1.83)0.17
 ≥3 years
  Cases/subcohort, na186/631219/614203/594226/575208/577
  Overall HRb (95% CI)1.001.10 (0.87–1.40)1.00 (0.79–1.28)1.08 (0.85–1.38)1.01 (0.78–1.29)0.94
  Placebo1.001.18 (0.70–1.98)1.33 (0.79–2.25)1.15 (0.69–1.91)1.04 (0.60–1.81)0.99
  α-Tocopherol only1.000.78 (0.49–1.23)0.79 (0.49–1.26)0.68 (0.42–1.10)0.58 (0.35–0.96)0.03
  Selenomethionine only1.001.05 (0.65–1.70)1.00 (0.61–1.65)1.29 (0.80–2.09)1.14 (0.69–1.86)0.40
  α-Tocopherol and selenomethionine1.001.56 (0.95–2.55)0.94 (0.57–1.53)1.37 (0.84–2.25)1.36 (0.82–2.24)0.44
  Any selenomethionine1.001.27 (0.90–1.79)0.99 (0.70–1.40)1.33 (0.94–1.88)1.28 (0.90–1.82)0.19
  Any α-tocopherol1.001.09 (0.78–1.52)0.87 (0.62–1.21)0.95 (0.67–1.35)0.90 (0.63–1.27)0.36
  • aThe subcohort contains both cases and non-cases, with overlap between case and subcohort numbers.

  • bHRs and 95% CIs based on proportional hazards regression, mutually adjusted for γ-tocopherol or α-tocopherol (continuous), with PSA, family history of prostate cancer, BMI, diabetes, cholesterol, and smoking status included in the models. Results are also age- and race-adjusted as a result of all models being stratified by age/race groups before being weighted and combined to generate summary statistics. The first plasma tocopherol quintile serves as referent category. Interaction P values for plasma α-tocopherol × smoking status are 0.95, 0.75, and 0.94 for the four intervention arm, any selenium, and any α-tocopherol strata (respectively). Interaction P values for plasma α-tocopherol × follow-up time to diagnosis are 0.21, 0.35, and 0.30 for the four intervention arm, any selenium, and any α-tocopherol strata (respectively).