Selenium and Lung Cancer: A Systematic Review and Meta Analysis

Selenium 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.Two 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.Selenium 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

Antioxidantes da dieta como inibidores da nefrotoxicidade induzida pelo antitumoral cisplatina Dietary antioxidants as inhibitors of cisplatin-induced nephrotoxicity

A cisplatina é uma droga antineoplásica altamente efetiva contra vários tipos de cânceres humanos, tais como tumores do testículo e ovário, câncer da cabeça e pescoço e câncer do pulmão. Entretanto, a nefrotoxicidade é um dos principais efeitos colaterais da terapia com a cisplatina. A gravidade da nefrotoxicidade induzida pela cisplatina está relacionada com a concentração de platina nos rins. As evidências mostram que a nefrotoxicidade induzida pela cisplatina é atribuída ao dano oxidativo resultante da geração de radicais livres, e que a administração de antioxidantes é eficiente na inibição destes efeitos colaterais. Uma abordagem alternativa para proteger os roedores dos efeitos colaterais da cisplatina é o uso de conhecidos antioxidantes da dieta. Alguns estudos têm sido realizados para diminuir a peroxidação lipídica e os efeitos citotóxicos induzidos pela cisplatina, com o emprego de antioxidantes da dieta, tais como, selenito de sódio, vitaminas C e E, curcumina e o carotenóide bixina. Nós sugerimos que aqueles antioxidantes da dieta têm efeito nefroprotetor, e que os mecanismos antioxidantes destes compostos deveriam ser explorados durante a quimioterapia com a cisplatina.<br>Cisplatin is a highly effective antineoplastic drug used against several types of human cancers, such as testicular and ovarian tumors; head and neck; and lung cancer. However, nephrotoxicity is one of the most important side-effects of cisplatin therapy. The severity of cisplatin nephrotoxicity is related to platinum concentration in the kidneys. There is a growing amount of evidence that cisplatin-induced nephrotoxicity is ascribed to oxidative damage resulting from free radical generation and that the administration of antioxidants is efficient in inhibiting these side effects. An alternative approach aiming to protect rodents against cisplatin side-effects is the introduction of known dietary antioxidants. Some studies have been conducted to decrease cisplatin-induced lipid peroxidation and cytotoxic effects by using such dietary antioxidants, including sodium selenite; vitamins C and E; curcumin and the carotenoid bixin. We suggest that these dietary antioxidants have a nephroprotective effect, and that their antioxidant mechanisms should be further explored during cisplatin chemotherapy