CHANGES IN TUMOR OXYGENATION DURING COMBINED TREATMENT WITH SPLIT-COURSE RADIOTHERAPY AND CHEMOTHERAPY IN PATIENTS WITH HEAD AND NECK-CANCER

Purpose: To evaluate the changes in tumor oxygenation during definitiv e split-course radiochemotherapy in locally advanced head and neck can cer (lymph nodes and primaries). Materials and methods: Twenty-four pa tients with locally advanced head and neck cancer were investigated pr etherapeutically and during a defined course of radiochemotherapy (RCT h) with a total dose of 70 Gy given in 35 fractions over 9 weeks (2-we ek break after 30 Gy). In weeks 1 and 6, the patients received chemoth erapy (5 FU and mitomycin C) concomitant with irradiation. The oxygen partial pressure measurements were carried out using polarographic nee dle probes in combination with a microprocessor-controlled device (pO( 2) histograph/KIMOC). Times of measurements were before therapy, at th e end of week 3 (30 Gy), after a 2-week break (30 Gy) and at the end o f therapy if measurable lesion was found (70 Gy). Results: There was a significant reduction in the median pO(2) (P < 0.005, n = 18) and an increase in the hypoxic fraction (defined as the percentage of pO(2) v alues of <5 mm Hg) after application of 30 Gy (P < 0.05, n = 18). This effect was partially reversed at the end of the 2-week break. During the break an increase in the median pO(2) (P = 0.05, n = 12) and a dec rease in the hypoxic fraction could be observed. Towards the end of th erapy (70 Gy) a significant decrease (P = 0.02, n = 13) in the median pO(2) occurred. Corresponding to this, the hypoxic fraction increased during the last 4 weeks of therapy (P = 0.06, n = 13). Conclusion: Sta tistically significant changes in oxygenation in locally advanced head and neck cancer were found during a split-course radiochemotherapy. T his information was obtained in a homogenous group of patients under w ell-defined therapeutic conditions. The decrease in the tumor oxygenat ion status at doses of 30 and 70 Gy are important findings because the y are in contrast to the concept of continuous improvement of the oxyg enation status during fractionated radiotherapy. (C) 1998 Elsevier Sci ence Ireland Ltd. All rights reserved.