Table 5. Association between baseline serum α-tocopherol and γ-tocopherol and risk of prostate cancer, stratified by smoking status, PLCO Study.

	Serum tocopherol quintiles
	1	2	3	4	5	p-trend	p-interactiona
α-Tocopherol, mg/L	≤12.3	>12.3 & ≤15.0	>15.0 & ≤18.7	>18.7 & ≤24.5	>24.5		0.049
Median, mg/L	10.4	13.8	16.7	20.6	30.6
Current smokers (n = 46/75)b	1.00	2.55 (0.56–11.71) c	0.51 (0.11–2.35)	1.65 (0.31–8.78)	0.51 (0.09–2.83)	0.37
Current smokers and recent quitters(<10 years ago) (n = 102/144)	1.00	0.93 (0.37–2.35)	0.47 (0.19–1.16)	0.55 (0.21–1.41)	0.39 (0.14–1.04)	0.06
Former smokers(quit ≥10 years ago)(n = 275/352)	1.00	0.80 (0.46–1.40)	0.91 (0.53–1.59)	0.70 (0.40–1.24)	0.77 (0.43–1.39)	0.44
Never-smokers (n = 244/247)	1.00	0.62 (0.34–1.15)	0.90 (0.47–1.71)	0.97 (0.50–1.90)	1.02 (0.51–2.05)	0.49
γ-Tocopherol, mg/L	≤1.38	>1.38 & ≤2.49	>2.49 & ≤3.48	>3.48 & ≤4.78	>4.78		0.28
Median, mg/L	0.96	1.94	3	4.05	5.83
Current smokers (n = 46/75)	1.00	2.33 (0.32–16.76)	3.68 (0.46–29.36)	1.60 (0.20–13.01)	1.73 (0.24–12.66)	0.80
Current smokers and recentquitters (<10 years ago)(n = 102/144)	1.00	3.31 (1.09–9.99)	4.65 (1.51–14.36)	1.61 (0.48–5.44)	2.95 (0.91–9.56)	0.55
Former smokers(quit ≥10 years ago) (n = 275/352)	1.00	1.60 (0.95–2.69)	1.41 (0.83–2.40)	1.32 (0.76–2.30)	1.13 (0.63–2.00)	0.92
Never-smokers (n = 244/247)	1.00	0.90 (0.47–1.69)	1.69 (0.91–3.15)	1.26 (0.67–2.38)	1.29 (0.65–2.59)	0.28

^aMultiplicative interaction tested using the log-likelihood ratio, comparing models with and without an interaction term of tocopherol quintiles crossed with a categorical smoking status variable.

^bNumbers are cases/controls.

^cValues are odds ratios (95% confidence intervals), based on unconditional logistic regression and adjusted for study center, serum cholesterol, serum β-carotene, age, time since initial screening, and year of blood draw.