Tumor hypoxia is the situation where tumor cells have been deprived of oxygen. As a tumor grows, it rapidly outgrows its blood supply, leaving portions of the tumor with regions where the oxygen concentration is significantly lower than in healthy tissues.
It is a well known fact in the research literature that ‘Hypoxia’ is a hallmark of solid tumors and these cells are more resistant to radiation and chemotherapy. Hypoxic cells have been found to be more invasive and metastatic, resistant to apoptosis (programmed cell death) and genetically unstable, therefore targeting these cells directly can be challenging as they are usually deep within a tumor.
The ‘presence or absence’ of oxygen during ‘Radiation Therapy‘ has a strong influence on the biological effect on ionizing radiation. Under hypoxic conditions it has been shown that cells obtain radio-resistance. To overcome this problem, radiation oncologists have developed powerful tools and approaches which enables a booster dose of radiation to be delivered to small target fractions in a malignant tumor.
New developments in cancer treatment are ‘Bioreductive drugs‘ which are clever drugs which only kill hypoxic cells. This therapy can be combined with radiation and chemotherapy ensuring both tumor types, ‘hypoxic‘ and ‘oxic‘ cells are killed off.