Normobaric oxygen treatment during radiotherapy for carcinoma of the uterine cervix. Results from a prospective controlled randomized trial

Background and purpose: Hypoxia, a frequent characteristic of cervical canc er, is associated with reduced sensitivity to irradiation and thus may be a source of radiotherapy failure. This study was planned to test the hypothe sis, that inhalation of oxygen during radiotherapy may increase the radiati on effect on the tumor and improve loco-regional control and overall surviv al. Material and methods: From 1963 to 1965, a consecutive series of 208 patien ts with cervical cancer stage II/III who were to be treated by external irr adiation plus radium inserts, were included in this study. They were random ly assigned to either receive oxygen inhalations during the radiotherapy se ssions or just breathing air. Due to technical reasons the oxygen group was divided. For the first 10 months, they did receive oxygen during the radiu m inserts only, the last 13 months during all radiotherapy sessions. Results: After median 33 years follow-up, there are no differences in overa ll survival, cancer-specific survival or loco-regional control. Subgroup an alysis shows significantly improved loco-regional control in the stage IIB patients, with squamous cell carcinoma who received oxygen during all radio therapy sessions. This improvement was especially pronounced among the pati ents who also received blood transfusions. Conclusions: There was no influence of normobaric oxygen treatment on the o verall outcome to radiotherapy in patients with stage II cervical cancer, b ut subgroup analyses support the hypothesis that there is tumor areas of hy poxia-based radioresistance that may be counteracted by oxygen administrati on. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.