Changes in oxygenation during radiotherapy in carcinoma of the cervix

Purpose: The aim of this study was to investigate changes in tumor oxygenat ion, assessed by polarographic needle electrode measurements, following fra ctionated external beam radiotherapy in carcinoma of the cervix. Methods and Materials: Normal and tumor tissue oxygenation was measured in 19 patients prior to radiotherapy and after 40-45 Gy of external beam radio therapy delivered in 20 fractions over 4 weeks. All measurements were perfo rmed during anesthesia, Results: There was no significant difference in the level of normal tissue oxygenation pre- and post radiotherapy. The individual patient median tumor pO(2) values ranged from 0 to 31 mmHg pre-radiotherapy and 1 to 61 mmHg po st-radiotherapy. The mean of the 19 median pO(2) values increased from 8 (S D +/- 10) mmHg to 20 (+/- 20) mmHg following external beam radiotherapy. Th e increase was significant by paired Wilcoxon test (p = 0.011). There was a lso a significant fall in the proportion of values < 5 mmHg (p = 0.040). Al though this value remained constant, or fell, in the majority of patients ( 15/19), it increased in 4 tumors. Tumor size pre- and post-radiotherapy did not correlate with the level of pretreatment oxygenation; neither did the change in tumor size and change in level of oxygenation. Conclusion: The level of tumor oxygenation increased in the majority of pat ients (15/19) following 40-45 Gy of radiotherapy in carcinoma of the cervix . (C) 1999 Elsevier Science Inc.