Published in Cancer Detection and Prevention 2000; 24(4):305-313.

A Case-Control Study of Toenail Selenium and Cancer of the Breast, Colon, and Prostate

Parviz Ghadirian, PhD,a,b Patrick Maisonneuve, PhD,c Chantal Perret, DEA,a Greg Kennedy PhD,d Peter Boyle, PhD,c Daniel Krewski, PhD,e and André Lacroix, MDf

aEpidemiology Research Unit, Research Center-CHUM, University of Montreal, and bResearch Centre, Hospital Sainte-Justine, Montreal, Quebec, Canada; cDivision of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy; dLaboratoire Polyfonctionnel, École Polytechnique, Université de Montreal, Montreal, Quebec, Canada; eDepartment of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada; and fLaboratory of Nutrition and Cancer and Department of Medicine, Research Center-CHUM, Montreal, Quebec, Canada

Address all correspondence and reprint requests to: Dr. Parviz Ghadirian, Epidemiology Research Unit, Research Center-CHUM, Hotel-Dieu, Pavilion Masson, 3850 St-Urbain, Montreal, Quebec, Canada H2W 1T8.

ABSTRACT: To study the possible role of dietary and supplementary selenium intake in the etiology of cancer, we carried out a case-control study of breast, colon, and prostate cancer in Montreal between 1989 and 1993. In this study, we were able to interview a total of 1,048 incidence cases of colon (402), breast (414) and prostate (232) cancer subjects and 688 population-based controls matched for age and gender. Of these, a total of 501 cancer cases and 202 controls produced toenail samples for their selenium concentrations, which were determined by neutron activation analysis. We found no association between toenail selenium and breast cancer (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.4 - 1.31) or prostate cancer (OR, 1.14; 95% CI, 0.46 - 2.83), though we did observe a statistically significant inverse association between toenail selenium level and the risk of colon cancer for both genders combined (OR, 0.42; 95% CI, 0.19 - 0.93; P = .009) and for female subjects (P = .050). We also found that nonsmoker case and control subjects had higher selenium in their toenail samples. This could be due either to the nature of tobacco, which reduces selenium absorption, or to smokers' consumption of certain foods containing less selenium. Further epidemiologic studies are required to clarify the role of selenium in the etiology of certain cancers.

KEY WORDS: breast, colon, prostate, cancer, selenium, risk, protection.