Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).
BACKGROUND
Secondary analyses of 2 randomized controlled trials and supportive epidemiologic and preclinical data indicated the potential of selenium and vitamin E for preventing prostate cancer.


OBJECTIVE
To determine whether selenium, vitamin E, or both could prevent prostate cancer and other diseases with little or no toxicity in relatively healthy men.


METHODS
A randomized, placebo-controlled trial (Selenium and Vitamin E Cancer Prevention Trial [SELECT]) of 35,533 men from 427 participating sites in the United States, Canada, and Puerto Rico randomly assigned to 4 groups (selenium, vitamin E, selenium + vitamin E, and placebo) in a double-blind fashion between August 22, 2001, and June 24, 2004. Baseline eligibility included age 50 years or older (African American men) or 55 years or older (all other men), a serum prostate-specific antigen level of 4 ng/mL or less, and a digital rectal examination not suspicious for prostate cancer.


METHODS
Oral selenium (200 microg/d from L-selenomethionine) and matched vitamin E placebo, vitamin E (400 IU/d of all rac-alpha-tocopheryl acetate) and matched selenium placebo, selenium + vitamin E, or placebo + placebo for a planned follow-up of minimum of 7 years and a maximum of 12 years.


METHODS
Prostate cancer and prespecified secondary outcomes, including lung, colorectal, and overall primary cancer.


RESULTS
As of October 23, 2008, median overall follow-up was 5.46 years (range, 4.17-7.33 years). Hazard ratios (99% confidence intervals [CIs]) for prostate cancer were 1.13 (99% CI, 0.95-1.35; n = 473) for vitamin E, 1.04 (99% CI, 0.87-1.24; n = 432) for selenium, and 1.05 (99% CI, 0.88-1.25; n = 437) for selenium + vitamin E vs 1.00 (n = 416) for placebo. There were no significant differences (all P>.15) in any other prespecified cancer end points. There were statistically nonsignificant increased risks of prostate cancer in the vitamin E group (P = .06) and type 2 diabetes mellitus in the selenium group (relative risk, 1.07; 99% CI, 0.94-1.22; P = .16) but not in the selenium + vitamin E group.


CONCLUSIONS
Selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men.


BACKGROUND
clinicaltrials.gov identifier: NCT00006392.
Lippman
Scott M
SM
Division of Cancer Medicine, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA. slippman@mdanderson.org
Klein
Eric A
EA
Goodman
Phyllis J
PJ
Lucia
M Scott
MS
Thompson
Ian M
IM
Ford
Leslie G
LG
Parnes
Howard L
HL
Minasian
Lori M
LM
Gaziano
J Michael
JM
Hartline
Jo Ann
JA
Parsons
J Kellogg
JK
Bearden
James D
JD
Crawford
E David
ED
Goodman
Gary E
GE
Claudio
Jaime
J
Winquist
Eric
E
Cook
Elise D
ED
Karp
Daniel D
DD
Walther
Philip
P
Lieber
Michael M
MM
Kristal
Alan R
AR
Darke
Amy K
AK
Arnold
Kathryn B
KB
Ganz
Patricia A
PA
Santella
Regina M
RM
Albanes
Demetrius
D
Taylor
Philip R
PR
Probstfield
Jeffrey L
JL
Jagpal
T J
TJ
Crowley
John J
JJ
Meyskens
Frank L
FL
Baker
Laurence H
LH
Coltman
Charles A
CA
D000368:Aged; D000975:Antioxidants / Q000627:therapeutic use*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000517:prevention & control; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D012643:Selenium / Q000627:therapeutic use*; D012645:Selenomethionine / Q000627:therapeutic use; D016896:Treatment Outcome; D014810:Vitamin E / Q000627:therapeutic use*; D024502:alpha-Tocopherol / Q000627:therapeutic use
D000975:Antioxidants; D014810:Vitamin E; D012645:Selenomethionine; D024502:alpha-Tocopherol; D012643:Selenium