Hypoxia and Carcinoma of the Cervix.
The article examines current laboratory and clinical information with respect to the relative importance of tumor hypoxia to the radiation control of carcinoma of the cervix. Its impact is difficult to quantify because of interrelated important parameters, which are also operational, including inherent radiosensitivity, reoxygenation, repair, and clonogenic cell proliferation. Strategies that have been investigated to modify the detrimental affects of hypoxia are reviewed including laboratory and clinical data examining modifications of oxygen delivery by the use of blood transfusion, erythropoietin and perfluorochemicals. Clinical data supporting their beneficial effects are inconclusive although extrapolation from animal data suggests that raising hemoglobin levels in anaemic patients before radiotherapy may be useful. The possible benefits for the use of hyperbaric oxygen in conjunction with hypofractionated radiation are discussed. Preclinical and clinical data on the use of hypoxia cell radiation sensitizes are reviewed. No benefit has been shown for patients with carcinoma of the cervix when treated with hypoxic cell radiation sensitizers in conjunction with radiation. Possible future directions for investigation of strategies to overcome hypoxia are discussed.
Thomas
GM
Division of Radiation Oncology, TOronto-Bayview Regional Cancer Centre, Toronto, Ontario, Canada