PARTIAL-PRESSURE OF OXYGEN IN THE TISSUE OF HUMAN HEAD AND NECK CANCERS DURING PRIMARY RADIATION TREATMENT AND CHEMOTHERAPY

Background: Experimental data have shown that hypoxic areas in tumors can increase their malignant potential and reduce their sensitivity to chemotherapy and radiation treatment. Until now, the only incomplete data on the oxygenation of human tumors during therapy have been avail able. Methods: The distribution of partial pressure of oxygen in malig nant head and neck processes was measured in four patients with lymph- node metastases by means of invasive computerized histography (system manufactured by Eppendorf). All patients received primary radiation tr eatment and chemotherapy with a two-week respite after 30 Gy and the f irst cycle of chemotherapy. The total dose consisted of 70 Gy in the t umor and two cycles of chemotherapy. Oxygen measurements were taken be fore the onset of treatment, before and after the respite, and after c ompletion of treatment. Results: In three of the four patients, we mea sured prominent hypoxic areas in the cancers with PO, values less than 5 mmHg. The average value was between 12 and 46 mmHg. We were impress ed by the observation that oxygenation appeared to improve in every ca ncer during the respite. Only the patient who showed good initial oxyg enation without any measurable hypoxic fraction suffered a complete re currence six weeks after the completion of therapy. Conclusions: Promi nent areas of hypoxic tissue are present in human head and neck cancer s. Radiation treatment and chemotherapy can alter the oxygenation. Fur ther studies are required to investigate the significance of the oxyge nation of human head and neck cancers and the changes occurring in it during different types of therapy in order to assess its clinical impa ct.