Updates on clinical studies of selenium supplementation in radiotherapy

Abstract

To establish guidelines for the selenium supplementation in radiotherapy we assessed the benefits and risks of selenium supplementation in radiotherapy. Clinical studies on the use of selenium in radiotherapy were searched in the PubMed electronic database in January 2013. Sixteen clinical studies were identified among the 167 articles selected in the initial search. Ten articles were observational studies, and the other 6 articles reported studies on the effects of selenium supplementation in patients with cancer who underwent radiotherapy. The studies were conducted worldwide including European, American and Asian countries between 1987 and 2012. Plasma, serum or whole blood selenium levels were common parameters used to assess the effects of radiotherapy and the selenium supplementation status. Selenium supplementation improved the general conditions of the patients, improved their quality of life and reduced the side effects of radiotherapy. At the dose of selenium used in these studies (200–500 μg/day), selenium supplementation did not reduce the effectiveness of radiotherapy, and no toxicities were reported. Selenium supplementation may offer specific benefits for several types of cancer patients who undergo radiotherapy. Because high-dose selenium and long-term supplementation may be unsafe due to selenium toxicity, more evidence-based information and additional research are needed to ensure the therapeutic benefits of selenium supplementation.

Protective effects of sodium selenite supplementation against irradiation-induced damage in non-cancerous human esophageal cells

“…Selenium exists in numerous chemical forms, of which the most studied are selenomethionine, sodium selenite, methylselenocysteine, 1,4-phenylenebis (methylene) selenocyanate and methylseleninic acid (9). Sodium selenite is the chemical form of selenium previously used in clinical studies of radiotherapy supplementation between 1987 and 2012 (7). Despite having been previously used as a complementary medicine during clinical radiotherapy (11,12), the effectiveness of selenium use in radiotherapy and the mechanisms underlying the effect of selenium in reducing the side effects of radiotherapy require further study (7).…”

“…It detoxifies reactive oxygen species (ROS) produced by radiation treatment (4,7). In human antioxidant systems, selenium acts in the form of selenocysteine, which is incorporated into various selenoproteins (8,9).…”

“…Sodium selenite is the chemical form of selenium previously used in clinical studies of radiotherapy supplementation between 1987 and 2012 (7). Despite having been previously used as a complementary medicine during clinical radiotherapy (11,12), the effectiveness of selenium use in radiotherapy and the mechanisms underlying the effect of selenium in reducing the side effects of radiotherapy require further study (7). Schleicher et al (13) and Rodemann et al (14) performed in vitro studies of selenium and radiotherapy and identified that sodium selenite has potential as a protective agent for non-cancerous tissues during radiotherapy (15).…”

Maternal selenium-supplementation at various stages of periconception period: influence on murine blastocyst morphology and implantation status

“…Selenium has many beneficial effects to animal and human health, but this trace mineral still has reported cases of toxicity [3, 6, 41, 42], when given in high dose [43] or in long-duration [44, 45]. Taking into consideration that the selenium dose used in this study is at a level established to have a protective effect based from Soudani et al, [18], the 25 days (pregestation-to-gestation) of selenium-supplementation might have caused a certain level of toxicity.…”

Nrf2‐modulation by seleno‐hormetic agents and its potential for radiation protection

“…Sodium selenite was oral administered in the dose range of 200–500 μg daily or 1,000 μg daily by infusion. Based on the results from 16 clinical trials, it was concluded that Se supplementation advanced the general condition of the patients and at the working doses, Se toxicity was not detected, and did not compromise the efficacy of radiotherapy . In line with these studies, Schilling et al recently reported that treatment with sodium selenite pentahydrate (140 μg/L) did not influence deoxyribonucleic acid (DNA) double‐strand break and radiosensitivity in breast cancer cell lines …”