Table 1. Epidemiological Studies on Selenium and Prostate Cancer^a.

—ordered by study design and publication year

1st Author, pub. Year, reference	Country	Cases/Controls	Results (RR comparing highest to lowest quantile)						Selenium assessment
			All cancer			Advanced cancer
			OR	95%CI	p-trend	OR	95%CI	p-trend	Specimen	Mean/medianb
Randomized Clinical Trial
Clark 1996[3]	United States	13/35c	0.37	0.18–0.71	0.002				Plasma (at baseline)	114
Nested Case-Control, Case-Cohort Studies or Cohort
Peters 2008	United States	830/34412	0.90	0.62–0.13	0.97	0.46	0.17–1.3	0.31	Supplement	26.6 μg in users
Peters 2007[27]	United States	724/879	0.84	0.62–1.14	0.70	0.62	0.30–1.29	0.57	Serum	141
Li 2004[19]	United States	586/577	0.78	0.54–1.13	0.16	0.52	0.28–0.98	0.05	Plasma	108
van den Brandt 2003[20]	Netherlands	540/1211	0.69	0.48–0.99	0.008	0.62	0.37–1.05	0.02	Toenails	0.55
Brooks 2001[24]	United States	52/996	0.24	0.08–0.77	0.01				Serum	120
Goodman 2001[25]	United States	235/456	1.02	0.65–1.60	0.69	0.76	0.34–1.71	0.35	Serum	114
Nomura 2000[21]	United States	249/249	0.5	0.3–0.9	0.02	0.3	0.1–0.8	0.01	Serum	132
Helzlsouer 2000[22]	United States	117/233	0.38	0.17–0.85	0.12				Toenails	0.79
Yoshizawa 1998[23]	United States	181/181				0.35	0.16–0.78	0.03	Toenails	0.96
Criqui 1991[43]	North America	6/12	Selenium levels lower in prostate cancer cases than controls by 20 ng/ml (p<0.1)						Plasma	149
Knekt 1990[26]	Finland	51/102	1.15	Not reported	0.71				Serum	58
Coates 1988[51]	United States	13/22	0.3	Not reported	0.18				Serum Plasma	162 148
Peleg 1985[50]	United States	14/28	Selenium levels not-significant higher in prostate cancer cases (0.120 μg/ml) than controls (0.117 μg/ml)						Serum	117
Willett 1983[49]	United States	11/22	Selenium levels lower in prostate cancer cases (0.128 μg/ml) than controls (0.139 μg/ml) (p=0.12)						Serum	139
Population-based Case-Control Studies
Allen 2004[16]	United Kingdom	300/300	1.24	0.73–2.10	0.58	0.78	0.27–2.25	0.48	Nails	0.61
Vogt 2003[17]	United States	212/233	0.71	0.39–1.28	0.11	0.75	0.32–1.80	0.49	Serum	137
Ghadirian 2000[18]	Canada	83/82	1.14	0.46–2.83	0.62				Toenails	0.91

^aEcologic studies and observational studies using dietary questionnaire data to assess selenium intake or patients with benign hyperplasia as controls were excluded

^bMean/median selenium levels in controls only, serum and plasma selenium levels in ng/ml and toenail selenium levels in ng/mg

^cNumber of prostate cancer cases in selenium supplementation group/placebo group