Ingrid moen affiliated with department of biomedicine, university of bergen email author . Linda e. b. stuhr affiliated with department of biomedicine, university of bergen 10.1007/s11523 012 0233 x hypoxia is a critical hallmark of solid tumors and involves enhanced cell survival, angiogenesis, glycolytic metabolism, and metastasis. Hyperbaric oxygen hbo treatment has for centuries been used to improve or cure disorders involving hypoxia and ischemia, by enhancing the amount of dissolved oxygen in the plasma and thereby increasing o₂ delivery to the tissue.

Studies on hbo and cancer have up to recently focused on whether enhanced oxygen acts as a cancer promoter or not. As oxygen is believed to be required for all the major processes of wound healing, one feared that the effects of hbo would be applicable to cancer tissue as well and promote cancer growth. Furthermore, one also feared that exposing patients who had been treated for cancer, to hbo, would lead to recurrence. Nevertheless, two systematic reviews on hbo and cancer have concluded that the use of hbo in patients with malignancies is considered safe. To supplement the previous reviews, we have summarized the work performed on hbo and cancer in the period 2004–2012. Based on the present as well as previous reviews, there is no evidence indicating that hbo neither acts as a stimulator of tumor growth nor as an enhancer of recurrence. On the other hand, there is evidence that implies that hbo might have tumor inhibitory effects in certain cancer subtypes, and we thus strongly believe that we need to expand our knowledge on the effect and the mechanisms behind tumor oxygenation.

Pubmed was searched for articles concerning hyperbaric oxygen hbo and cancer for the period from 2004 to 2012, using the mesh search terms hyperbaric oxygenation and/or hyperoxia and neoplasms . A total of 28 articles were found relevant, directly involving the use of hbo as a stand alone or as adjuvant treatment on different cancer types. We focused on growth, cell survival, angiogenesis, and metastasis observed in hbo treated cancers the last 9 years, both as stand alone and adjuvant treatment, and compared them to older publications involving the selected topic. Summary of the hypoxia induced factors influencing cancer growth and progression the dual role of oxygen leads to the question: will lack of oxygen inhibit cancer progression, or is hyperoxygenating the tumor tissue the way to go in order to prevent cancer growth and development? hyperbaric oxygen can be used to overcome hypoxia. Hbo is based on administration of 100 % oxygen at higher than normal atmospheric pressure. Hbo treatment enhances the amount of dissolved oxygen in the plasma, thereby increasing o₂ tissue delivery independent of hemoglobin 10 . As in normal tissue, the po₂ in cancer tissue increases significantly during hbo exposure 11 .

Easy Narrative Essay

Thus, elevation of the tumor oxygen pressure has been shown to be preserved clinically for approximately 30 min after hbo exposure 12. Hbo therapy is today accepted and routinely used for many disorders, related to both ischemia and/or hypoxia 10 . Hbo is considered safe and complications are rare using today’s standard treatment protocols. The undersea and hyperbaric medical society has a list of approved indications for hbo therapy, including decompression sickness, severe carbon monoxide poisoning, nonhealing wounds, and late radiation injury. As oxygen is believed to be required for all the major processes involved in wound healing, including resistance to infection, activation of fibroblasts, collagen deposition, angiogenesis, and epithelization 14 , it has been feared that hbo would have a proliferative effect in cancers. Thus, for many decades, the focus has been to elucidate if hbo promotes cancer growth. The reviews included both experimental and clinical studies using different types of cancers, with and without additional therapy, and the results showed varied responses.

History Papers History Papers

Nevertheless, the conclusion in both reviews was that hbo did not promote cancer growth, and that the use of hbo in patients with malignancies was considered safe. Interestingly, evidence implies that cancer tissue might differ in response from normal tissue. The studies performed on hbo and cancer are complex due to a wide range of experimental designs and treatment regimes. Nevertheless, in an attempt to clarify the differences in response to oxygenation, we have summarized the literature concerning the effect of hbo on crucial hallmarks of cancer, the effect of hbo on chemo and radiation therapy, and in addition we have clustered the different cancer type responses. Studies of prolonged hyperoxia have shown that elevated levels of reactive oxygen species ros overwhelm the antioxidant defense and lead to cellular damage and possible organ dysfunction 17 .

The tissue damage is found to be dependent on the cell type, concentration of oxygen, and the duration of the exposure. 17 have summarized the molecular mechanisms behind hyperoxia induced cell death, revealing a complex signaling system including protein kinases and receptors such as rage, cxcr2, tlr3, and tlr4. Two in vitro studies on mammary and oral cancer cells, respectively, showed no change in apoptosis after hbo 18. 20 observed activation of the pro apoptotic pathway mapk and downregulation of the anti apoptotic erk pathway in hematopoetic cells after hbo.

Buy Mba Dissertation

Additionally, a study of hbo using osteosarcoma cells also demonstrated induction of apoptosis 21 . In two different animal models, gliomas and mammary tumors, respectively, our group has demonstrated induction of cell death after hbo treatment 22 – 24 . Furthermore, reduced cell proliferation, together with a significant change in histology, has also been shown after hbo treatment in dmba induced mammary tumors in vivo 22.

My Garden Essay Writing

18 observed the same reduction in cell proliferation in their mammary in vitro study. In addition, two recent studies on osteosarcoma cells 21 and nasopharyngeal carcinoma 25 support inhibition of cell division after hbo treatment. Together, this might imply that changes in oxygen concentration influence antioxidant pathways 26 , leading to a change in cell survival signaling. However, the picture is complex, and mechanistic studies are required before any final conclusions can be drawn. Today, angiogenesis is proposed to be a key factor for cancer growth and metastasis. Thus, large experimental studies and clinical trials have investigated the effect of antiangiogenic therapies in the treatment of cancers.

Aqa A2 Ict Coursework Help

Since hbo in general has been shown to promote cellular and vascular proliferation in normal tissue and wounds although the mechanisms are not fully understood , it was assumed that it would also induce angiogenesis in cancers. In contrary to what is expected and addressed in the literature, hbo has been shown to induce an antiangiogenic effect in two mammary tumor models 22. Furthermore, multiple studies showed no change in angiogenesis after hbo treatment 27 – 32 .