title: Reactive Oxygen and Nitrogen Species in Carcinogenesis: Implications of Oxidative Stress on the Progression and Development of Several Cancer Types.
abstract: BACKGROUND
  The body of evidence available from published literature during the past three decades indicates that reactive oxygen species and reactive nitrogen species can induce, promote and modulate carcinogenesis.
  
  
  OBJECTIVE
  The purpose of this review was to present the current status of knowledge on the possible role of oxidative/nitrosative stress in the development and progression of several human cancers. Moreover, we discuss briefly the formation and decomposition of oxygen and nitrogen species within cells and their physiological and damaging influences. Given that some antitumor treatments are based on the formation of ROS, we also summarize what is currently known about supplementing the diet with antioxidants.
  
  
  METHODS
  We conducted literature searches to review the recent progress toward the potential role of reactive oxygen and nitrogen species and associated oxidative stress in carcinogenesis.
  
  
  RESULTS
  The epidemiological and laboratory studies showed that excessive production of reactive oxygen/ nitrogen species may lead to consequent alteration in the intracellular homeostasis and cause damage to all important cellular components when the excess of oxidants is not balanced by antioxidant defence and/or DNA repair mechanisms. Chronic oxidative stress can drive carcinogenesis by altering expression of cancer-related genes causing mutation and transformation.
  
  
  CONCLUSIONS
  There is now common agreement that reactive oxygen and nitrogen species are involved in the development and progression of several human cancers like breast, prostate, colorectal, gynecological, cervical, eye, skin, leukemia, gastric. Antioxidant supplements at low doses can promote health, while excess supplementation can be harmful and even carcinogenic.
authors.affiliation: Department of Prevention and Occupational Therapy, Faculty of Physical Culture and Health Promotion, University of Szczecin, Szczecin. Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kruk
authors.affiliation: Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Giza 12622. Egypt.
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
mesh_terms: D063646:Carcinogenesis / Q000473:pathology*; D006801:Humans; D009369:Neoplasms / Q000145:classification / Q000503:physiopathology*; D018384:Oxidative Stress; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species
keywords: Antioxidant defence; antioxidant supplements; bimodal action; cancer diseases; oxidant damage; oxidative stress; reactive oxygen and nitrogen species