Hyperbaric oxygen in cancer
Poorly vascularized areas of the tumor may be
perfused, through sub-lethal levels, by cytotoxic agents, thus generating an
acquired resistance to chemotherapy. A study published in Nature magazine has
also shown that hypoxia may be responsible for a variety of growth modulation
effects that could generate an advantage of cancer cell growth.
Yang and his research team found that the hypoxia-induced expression of factor-1 (HIF-1), suggested to be an endogenous marker of tumor hypoxia, significantly affected the overall survival and the disease-free survival of osteosarcoma patients.
Antitumor effect of hyperbaric oxygen therapy
HBOT dramatically increases the amount of oxygen dissolved in the plasma,
oxygenates the hypoxic tissues and promotes neovascularization, eventually
leading to increased blood flow. These features of hyperbaric oxygen therapy
increase the partial pressure of oxygen inside the tumor and make it more
susceptible to radiotherapy.
HBOT has been extensively and successfully used in radiotherapy to increase radiation sensitivity and tumor oxygenation. In the same way, hyperbaric oxygen therapy enhances the perfusion of chemotherapeutic agents into hypoxic tumors and the susceptibility of tumor cells to such drugs.
Several studies have suggested that hyperbaric oxygen therapy can promote the growth or recurrence of malignancy by promoting angiogenesis, while other studies have shown inhibitory effects on tumor growth. However, two independent research groups have recently reviewed experimental and clinical data from the literature of the past 50 years and concluded that intermittent exposure to HBOT had no stimulatory effects on primary or metastatic cancer growth.
Currently, HBOT is used clinically in combination with radiotherapy and chemotherapy as a treatment approach of malignant tumors.