Selenium is a micronutrient mineral found mainly in soils. Studies on selenium have increased rapidly worldwide especially after it has been shown to reduce the risk of certain types of cancer in humans and animals. The exact mechanism of action on how selenium inhibits diseases, in particular cancer, is still unknown. To date, the use of selenium in preventing or treating diseases is limited. However, many aspects about the biochemistry of selenium have been identified. This article reviews a number of key clinical, experimental and epidemiological studies on selenium as an anti-carcinogenic agent for some types of cancers. Some nutritional information on selenium and its recommended intake are also included. More clinical and experimental studies are needed to confirm previous findings on the role of selenium as an anticarcinogenic agent.
Selenium ; Selenium measurement ; Minerals ; experiment ; Clinical

While cancer is considered to be one of the leading causes of death worldwide, there is a growing scientific and public interests on selenium as a dietary and antioxidant of many diseases, in particular, cancer. Despite advanced technology and significant improvement of surgical, chemical, hormonal and radio therapies, hepatocellular carcinoma (HCC) is still common in Asia and Africa and is increasing in the developed countries. Prognosis of HCC at an early stage is still challenging. At the moment, combination of Alpha feto protein (AFP) and ultrasonography tests offers more accurate and sensitive results for the diagnosis of HCC. Selenium (also known as the moon element) has been recognized for almost 49 years as an antioxidant and anti cancer agent. The weight of evidence supports the position of selenium as an anti cancer agent for HCC but the molecular mechanism of how selenium inhibits HCC is still unknown. Numerous theories have been proposed and selenium induced apoptosis and cell cycle arrest is the predominant one so far.

Background and objective The expression of various trace elements and markers in lung cancer is controversial. The aim of this study is to evaluate the presence of calcium (Ca), copper (Cu), iron (Fe) and carcinoembryonic antigen (CEA) in cancerous untreated lung tissues and to determine a possible association between these markers and lung cancer.Methods Fourty-eight cancerous lung tissue blocks, from Sultan Qaboos University Hospital, Sultanate of Oman, were studied. Fe, Ca, Cu, and CEA were demonstrated in the tissue blocks using Perl's Prussian blue, Von Kossa's, modified rhodanine and immunohistochemical staining methods, respectively.Results Twenty-three of 48 specimens showed positive Fe staining, 2 showed positive Ca staining and Cu was absent in all specimens. 93.7% expressed CEA in varying degree of positivity. 81.25% of these sections showed high expression of CEA. Conclusion Tissue concentrations of trace elements were not elevated in lung cancer and therefore cannot be considered as a potential marker. Despite the low sensitivity and specificity of CEA as previously reported, tissue CEA should be considered as a potential marker in the evaluation of lung cancer.