Selenium and Lung Cancer: A Systematic Review and Meta Analysis

Abstract

BackgroundSelenium is a natural health product widely used in the treatment and prevention of lung cancers, but large chemoprevention trials have yielded conflicting results. We conducted a systematic review of selenium for lung cancers, and assessed potential interactions with conventional therapies.Methods and FindingsTwo independent reviewers searched six databases from inception to March 2009 for evidence pertaining to the safety and efficacy of selenium for lung cancers. Pubmed and EMBASE were searched to October 2009 for evidence on interactions with chemo- or radiation-therapy. In the efficacy analysis there were nine reports of five RCTs and two biomarker-based studies, 29 reports of 26 observational studies, and 41 preclinical studies. Fifteen human studies, one case report, and 36 preclinical studies were included in the interactions analysis. Based on available evidence, there appears to be a different chemopreventive effect dependent on baseline selenium status, such that selenium supplementation may reduce risk of lung cancers in populations with lower baseline selenium status (serum<106 ng/mL), but increase risk of lung cancers in those with higher selenium (≥121.6 ng/mL). Pooling data from two trials yielded no impact to odds of lung cancer, OR 0.93 (95% confidence interval 0.61–1.43); other cancers that were the primary endpoints of these trials, OR 1.51 (95%CI 0.70–3.24); and all-cause-death, OR 0.93 (95%CI 0.79–1.10). In the treatment of lung cancers, selenium may reduce cisplatin-induced nephrotoxicity and side effects associated with radiation therapy.ConclusionsSelenium may be effective for lung cancer prevention among individuals with lower selenium status, but at present should not be used as a general strategy for lung cancer prevention. Although promising, more evidence on the ability of selenium to reduce cisplatin and radiation therapy toxicity is required to ensure that therapeutic efficacy is maintained before any broad clinical recommendations can be made in this context.

Selenium biochemistry and its role for human health

“…For example, a study noticed that Se supplementation associates with a reduced risk of lung cancers in populations with baseline serum Se level o106 ng mL À1 , whereas increases the risk in those with Se level >121.6 ng mL À1 . 265 A similar relation was observed in a metaanalysis on prostate cancer, where plasma/serum Se negatively correlated with prostate cancer risk only below 170 ng mL À1 . 253 These findings suggest that Se exhibits a U-shape relation with cancer risk, in analogy with many other antioxidants.…”

Analysis of serum levels of 15 trace elements in breast cancer patients in Shandong, China

“…In contrast, manganese divalent cations are required for colon cancer cells to bind to extracellular matrix proteins during migration and metastasis. Either too low or too high level of selenium is associated with increased risk of malignancies (Fritz et al 2011;Jaworska et al 2013;Lener et al 2013). Selenium supplementation was reported to be associated with decreased risk of prostate, colon, and lung cancers, but increased risk for breast cancer (Duffield-Lillico et al 2002).…”

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

“…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). At least 25 selenoproteins have been identified in humans, including glutathione peroxidase (GPx), thioredoxin reductases, iodothyronine deiodinase and the selenoproteins P, W and R (10).…”

“…At least 25 selenoproteins have been identified in humans, including glutathione peroxidase (GPx), thioredoxin reductases, iodothyronine deiodinase and the selenoproteins P, W and R (10). 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).…”