Abstract
Low oxygen condition or hypoxia is a distinguishing feature of the tumor microenvironment, which is a well-recognized factor responsible for the limited efficacy of traditional modes of cancer treatments, such as-radiotherapy, chemotherapy and photodynamic therapy. However, oxygen therapy can reverse the hypoxia-mediated de-sensitization of hypoxic tumor cells towards the conventional cancer treatments. The efficacy of photodynamic, drugs or radiation routines is enhanced whenever oxygen therapy is coupled with conventional treatment regimes. Additionally, a significant reduction in tumor mass post-oxygen therapy is evident, irrespective of coupling it with the conventional therapy. Hyperbaric Oxygen therapy (HBOT) was earlier used in cancer treatments. Nevertheless, untargeted application of HBOT comes with severe side-effects. This drawback limits the tumor oxygenation strategy to the pre-clinical stage. However recent studies demonstrate a large number of strategies such as use of manganese oxide based depots for site specific oxygen delivery and breathing of excess of oxygen with reduced time etc., all have been discovered to achieve oxygenation of hypoxic tumor micro environment. This article reviews the important progresses made in the field of oxygen therapy. This study will be helpful in developing new therapeutic methods based on the application of oxygen, which can bypass hypoxia-induced resistance to traditional therapeutic regimes.
