Polarographic measurement of pO2 in cervix carcinoma

The outcome of radiation therapy of cervix carcinoma might depend on the oxygenation of the tumor tissue. An adequate method for measurement of tumor oxygen tension (pO2) is therefore needed. The purpose of the work reported here was dual: (1) to investigate whether polarographic pO2 measurements with the Eppendorf pO2 Histograph 6650 are sufficiently sensitive to detect differences in tumor pO2 before and after blood transfusion of anemic patients and between poorly and well-vascularized tumor tissue, and (b) to investigate whether accurate tumor, pO2 measurements require extensive mapping of tumor temperature and the avoidance of anesthesia. Nineteen patients with squamous cell carcinoma of the uterine cervix FIGO stages Ib to IVb were included in the study. Vascular density was determined by histological examination of tumor biopsies. Propofol was used as a single anesthetic agent. Tumor pO2 distributions recorded before and after the administration of propofol were not different (P > 0.05). The temperatures measured in the tumor periphery and center did not differ from the rectal temperature (P > 0.05), suggesting that tumor pO2 measurements can be based on the rectal temperature. Increased hemoglobin concentrations after blood transfusion resulted in increased tumor oxygenation in 50% of the patients (P < 0.001). The pO2 frequency distributions of the susceptible tumors showed increased 50th percentiles but unchanged 10th percentiles, suggesting that transfusion cannot reduce the fraction of radiation-resistant hypoxic tumor cells extensively. Tumor tissue with high vascular density showed higher pO2 values than tumor tissue with low vascular density (P < 0.001). In conclusion, polarographic measurement of tumor pO2 with the Eppendorf pO2 Histograph 6650 is a sensitive method for assessment of the oxygenation of cervix carcinoma. Reliable tumor pO2 measurements can be performed in patients given propofol anaesthesia and without extensive mapping of tumor temperature.