Oxygenation of head and neck cancer: changes during radiotherapy and impact on treatment outcome

Background rnd purpose: To evaluate the long term clinical significance of tumor oxygenation in a population of head and neck cancer patients receivin g radiotherapy and to assess changes in tumor oxygenation during the course of treatment. Methods and materials: Patients with head and neck cancer receiving primary RT underwent pretreatment polarographic tumor oxygen measurement of the pr imary site or a metastatic neck lymph node. Treatment consisted of once dai ly (2 Gy/fraction to a total dose of 66-70 Gy) or twice daily irradiation ( 1.25 Gy/fraction to 70-75 Gy) to the primary site. Twenty-seven patients un derwent a second series of measurements early in the course of irradiation. Results: Sixty-three patients underwent pretreatment tumor oxygen assessmen t (primary site, n = 24: nodes, n = 39). The median pO(2) for primary lesio ns was 4.8 mmHg, and it was 4.3 mmHg for cervical nodes. There was a weak a ssociation between anemia and more poorly oxygened tumors, but many non-ane mic patients still had poorly oxygenated tumors. Repeat assessments of tumo r oxygenation after 10-15 GS' were unchanged compared to pretreatment basel ines. Poorly oxygenated nodes pretreatment were more likely to contain viab le residual disease at post-radiation neck dissection. Median follow-up tim e for surviving patients was 20 months (range 3-50 months). Hypoxia (tumor median pO(2) <10 mmHg) adversely affected 2 year local-regional control (30 vs. 73%, P = 0.01), disease-free survival (26 vs. 73%, P = 0.005), and sur vival (35 vs. 83%, P = 0.02). Conclusion: Tumor oxygenation affects the prognosis of head and neck cancer independently of other known prognostic variables. This parameter may be a useful tool for the selection of patients for investigational treatment st rategies. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.