ABSTRACT
Stress contributes to various aspects of malignancy and could influence survival in laryngeal cancer patients. Among antioxidant mechanisms, zinc and the antioxidant enzymes superoxide dismutase 2, catalase and glutathione peroxidase 1 play a major role. The aim of this study was a prospective evaluation of the survival of patients with laryngeal cancer in relation to serum levels of zinc in combination with functional genotype differences of three key antioxidant enzymes. The study group consisted of 300 patients treated surgically for laryngeal cancer. Serum zinc levels and common polymorphisms in SOD2, CAT and GPX1 were analyzed. The risk of death in patients with the lowest zinc levels was increased in comparison with patients with the highest levels. Polymorphisms of antioxidant genes by themselves were not correlated with survival, however, serum zinc level impact on survival was stronger for SOD2 TC/TT and CAT CC variants. GPX1 polymorphisms did not correlate with zinc levels regarding survival. In conclusion, serum zinc concentration appears to be an important prognostic factor for survival of patients diagnosed with laryngeal cancer. When higher zinc levels were correlated with polymorphisms in SOD2 and CAT a further increase in survival was observed.
Subject(s)
Genotype , Laryngeal Neoplasms , Oxidative Stress , Zinc/blood , Adult , Aged , Aged, 80 and over , Disease-Free Survival , Female , Humans , Laryngeal Neoplasms/blood , Laryngeal Neoplasms/genetics , Laryngeal Neoplasms/mortality , Male , Middle Aged , Neoplasm Proteins/blood , Neoplasm Proteins/genetics , Survival RateABSTRACT
[This corrects the article DOI: 10.1371/journal.pone.0184873.].
ABSTRACT
BACKGROUND: Observational studies have reported an inverse relationship between selenium status (blood or toenail) and the risk of laryngeal cancer; however, the impact of low serum selenium level on survival has not been evaluated. METHODS: We conducted a prospective study of 296 patients diagnosed with laryngeal cancer in Szczecin, Poland. Serum selenium was measured at diagnosis and prior to treatment. Patients were followed from the date of diagnosis to death at five years. Vital status was obtained by linkage to the Polish National Death Registry. RESULTS: The five-year survival after diagnosis was 82.0% (95% CI: 68% to 91%) for individuals in the highest quartile of serum selenium (> 66.8 µg/L) and was 28.6% (95% CI 19% to 42%) for individuals in the lowest quartile (<50.0 µg/L). In an age- and sex-adjusted analysis, the hazard ratio (HR) for death from all causes was 7.01 (95% CI 3.81 to 12.9) for patients in the lowest quartile of serum selenium, compared to those in the highest quartile. The corresponding multivariate HR was 3.07 (95% CI 1.59 to 5.94). CONCLUSIONS: This study suggests that a selenium level in excess of 70 µg/L is associated with improved outcome among patients undergoing treatment for laryngeal cancer. Further studies are needed to evaluate if selenium supplementation to achieve this level might improve overall prognosis.
