Purpose: To evaluate the changes in tumor oxygenation during definitive split-course radiochemotherapy in locally advanced head and neck cancer (lymph nodes and primaries).
Materials and methods: Twenty-four patients with locally advanced head and neck cancer were investigated pretherapeutically and during a defined course of radiochemotherapy (RCTh) with a total dose of 70 Gy given in 35 fractions over 9 weeks (2-week break after 30 Gy). In weeks 1 and 6, the patients received chemotherapy (5 FU and mitomycin C) concomitant with irradiation. The oxygen partial pressure measurements were carried out using polarographic needle probes in combination with a microprocessor-controlled device (pO2 histograph/KIMOC). Times of measurements were before therapy, at the end of week 3 (30 Gy), after a 2-week break (30 Gy) and at the end of therapy if measurable lesion was found (70 Gy).
Results: There was a significant reduction in the median pO2 (P < 0.005, n = 18) and an increase in the hypoxic fraction (defined as the percentage of pO2 values 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 PO2 (P = 0.05, n = 12) and a decrease in the hypoxic fraction could be observed. Towards the end of therapy (70 Gy) a significant decrease (P = 0.02, n = 13) in the median pO2 occurred. Corresponding to this, the hypoxic fraction increased during the last 4 weeks of therapy (P = 0.06, n = 13).
Conclusion: Statistically significant changes in oxygenation in locally advanced head and neck cancer were found during a split-course radiochemotherapy. This information was obtained in a homogenous group of patients under well-defined therapeutic conditions. The decrease in the tumor oxygenation status at doses of 30 and 70 Gy are important findings because they are in contrast to the concept of continuous improvement of the oxygenation status during fractionated radiotherapy.