Authors
Clark LC. Combs GF Jr. Turnbull BW. Slate EH. Chalker DK. Chow J. Davis
LS. Glover RA. Graham GF. Gross EG. Krongrad A. Lesher JL Jr. Park HK.
Sanders BB Jr. Smith CL. Taylor JR.
Institution
Arizona Cancer Center, College of Medicine, University of Arizona, Tucson,
USA.
Title
Effects of selenium supplementation for cancer prevention in
patients with carcinoma of the skin. A randomized controlled trial.
Nutritional Prevention of Cancer Study Group [see comments] [published
erratum appears in JAMA 1997 May 21;277(19):1520].
Comments
Comment in: JAMA 1996 Dec 25;276(24):1984-5, Comment in: JAMA 1997 Mar
19;277(11):880; discussion 881, Comment in: JAMA 1997 Mar 19;277(11):880-1;
discussion 881
Source
JAMA. 276(24):1957-63, 1996 Dec 25.
Abstract
OBJECTIVE: To determine whether a nutritional supplement of
selenium will decrease the incidence of cancer. DESIGN: A
multicenter, double-blind, randomized, placebo-controlled cancer prevention
trial. SETTING: Seven dermatology clinics in the eastern United States.
PATIENTS: A total of 1312 patients (mean age, 63 years; range, 18-80 years)
with a history of basal cell or squamous cell carcinomas of the skin were
randomized from 1983 through 1991. Patients were treated for a mean (SD) of
4.5 (2.8) years and had a total follow-up of 6.4 (2.0) years. INTERVENTIONS:
Oral administration of 200 microg of selenium per day or
placebo. MAIN OUTCOME MEASURES: The primary end points for the trial were the
incidences of basal and squamous cell carcinomas of the skin. The secondary
end points, established in 1990, were all-cause mortality and total cancer
mortality, total cancer incidence, and the incidences of lung, prostate, and
colorectal cancers. RESULTS: After a total follow-up of 8271 person-years,
selenium treatment did not significantly affect the
incidence of basal cell or squamous cell skin cancer. There were 377 new
cases of basal cell skin cancer among patients in the
selenium group and 350 cases among the control group
(relative risk [RR], 1.10; 95% confidence interval [CI], 0.95-1.28), and 218
new squamous cell skin cancers in the selenium group and 190
cases among the controls (RR, 1.14; 95% CI, 0.93-1.39). Analysis of secondary
end points revealed that, compared with controls, patients treated with
selenium had a nonsignificant reduction in all-cause
mortality (108 deaths in the selenium group and 129 deaths
in the control group [RR; 0.83; 95% CI, 0.63-1.08]) and significant
reductions in total cancer mortality (29 deaths in the
selenium treatment group and 57 deaths in controls [RR,
0.50; 95% CI, 0.31-0.80]), total cancer incidence (77 cancers in the
selenium group and 119 in controls [RR, 0.63; 95% CI,
0.47-0.85]), and incidences of lung, colorectal, and prostate cancers.
Primarily because of the apparent reductions in total cancer mortality and
total cancer incidence in the selenium group, the blinded
phase of the trial was stopped early. No cases of selenium
toxicity occurred. CONCLUSIONS: Selenium treatment did not
protect against development of basal or squamous cell carcinomas of the skin.
However, results from secondary end-point analyses support the hypothesis
that supplemental selenium may reduce the incidence of, and
mortality from, carcinomas of several sites. These effects of
selenium require confirmation in an independent trial of
appropriate design before new public health recommendations regarding
selenium supplementation can be made