Hypoxia as a determinant factor in radiotherapy? Where are we?

The author reviews the current state of knowledge of the role of hypoxia as a determinant factor in cancer radiotherapy, and concludes that it is reasonable to suppose that before treatment between one-third and one-half of breast, cervix and head and neck carcinomas contain radiobiologically hypoxic cells. The development of pO2 measurements in human tumours together with more experimental data from biopsies and the search for relationships between measured pO2 and the outcome of radiotherapy are called for. (UK)