Purpose: Tumor hypoxia may be an important factor predicting relapse following radiation therapy. This study was designed to determine the relationship between the oxygenation parameters measured using a polarographic oxygen electrode, prior to and during treatment in patients with cervix cancer, and to assess these results with regard to patient survival.
Materials and methods: Forty-three patients had pretreatment oxygen assays performed and measurements repeated following external beam radiation to a median dose of 50 Gy (range 26-52 Gy). Stage distribution showed 15 patients in Stage IB, 17 in Stage II, and 11 in Stage III. The median tumor size was 5 cm (range 3-10 cm).
Results: The median proportion of pO2 values <5 mm Hg (the HP5) was 41% following radiation, and the median pO2 was 12 mm Hg. These results were not significantly different from the pretreatment HP5 or pO2 of 37% and 12 mm Hg, respectively. Disease-free survival at 2 years was 50% in patients with posttreatment HP5 < or =50%, compared to 60% when posttreatment HP5 was >50% (p = 0.35).
Conclusions: Unlike pretreatment results, tumour oxygenation measured following external radiation does not appear to be a useful predictive assay in patients with cervical cancer.