Table 4.

Associations of serum concentrations of retinol and α-carotene with risk of total, lower-, and higher-grade prostate cancer, stratified by reason for biopsy, in the placebo arm of the PCPTa

OutcomeCases/controlsTotalCases/controlsGleason 2–6Cases/controlsGleason 7–10
Retinol
For-cause
 Q1b80/252Ref.55/252Ref.22/252Ref.
 Q2100/2531.19 (0.84–1.67)65/2531.11 (0.74–1.66)30/2531.31 (0.73–2.34)
 Q3123/2521.41 (1.01–1.98)90/2521.47 (1.00–2.16)28/2521.23 (0.68–2.23)
 Q4127/2521.43 (1.02–2.01)77/2521.24 (0.83–1.84)44/2521.91 (1.10–3.31)
 P trend0.020.160.02
Not-for-cause
 Q1115/252Ref.94/252Ref.16/252Ref.
 Q2128/2531.05 (0.77–1.43)105/2531.04 (0.74–1.45)18/2531.12 (0.56–2.26)
 Q3144/2521.12 (0.83–1.53)120/2521.12 (0.81–1.55)20/2521.26 (0.63–2.51)
 Q4158/2521.21 (0.89–1.64)129/2521.17 (0.85–1.62)26/2521.64 (0.85–3.17)
P trend0.180.290.12
P interactionc,d0.980.2960.94
α-Carotene
For-cause
 Q1102/253Ref.66/253Ref.31/253Ref.
 Q297/2520.88 (0.63–1.23)65/2520.90 (0.61–1.33)30/2520.92 (0.54–1.58)
 Q3101/2520.90 (0.64–1.25)69/2520.93 (0.63–1.38)27/2520.82 (0.47–1.44)
 Q4130/2521.12 (0.81–1.56)87/2521.12 (0.76–1.64)36/2521.17 (0.68–2.00)
P trend0.440.520.66
Not-for-cause
 Q191/253Ref.77/253Ref.13/253Ref.
 Q2143/2521.50 (1.09–2.07)119/2521.45 (1.03–2.04)19/2521.49 (0.71–3.12)
 Q3161/2521.70 (1.23–2.34)127/2521.53 (1.09–2.16)28/2522.30 (1.14–4.64)
 Q4150/2521.59 (1.14–2.21)125/2521.49 (1.05–2.12)20/2521.79 (0.84–3.82)
P trend0.0070.0370.067
P interaction0.730.940.44
  • aAssociations adjusted for age, race, family history of prostate cancer, and serum cholesterol.

  • bQuartiles of serum concentration of retinol and carotenoids were defined based on values in all controls (finasteride and placebo arms combined). Quartiles 1, 2, 3, and 4, respectively, were defined using the following stratum-specific cutoffs. Retinol: <0.58 μg/dL, 0.58 to <0.67 μg/dL, 0.67 to <0.77 μg/dL, >0.77 μg/dL; α-carotene: <0.03 μg/dL, 0.03 to <0.04 μg/dL, 0.04 to <0.7 μg/dL, >0.7 μg/dL.

  • cTo calculate interaction P value, controls are also stratified by reason for biopsy.

  • dP value tests for interaction between serum quartile (as a trend ordinal value) and stratification factor.