Intratumoral pO 2-measurements as predictive assay in the treatment of carcinoma of the uterine cervix

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Background: Several studies have shown that pretreatment oxygenation status of cervical tumors measured with a polarographic oxygen electrode could be a predictive factor for radiation response and survival. The purpose of this study was to evaluate the impact of intratumoral pO 2 levels and hypoxic fractions on local control and disease free survival employing a standardized measuring procedure under routine conditions. Materials and methods: Between April 1994 and December 1997 pO 2 measurements were performed prior to radiotherapy with an Eppendorf histograph in 51 evaluable patients with primary cervical carcinoma. All patients were treated with curative intent by combined external beam therapy (median total dose 49.6 Gy) and 3–6 applications of high dose rate- (7 Gy/fr. at point ‘A’) or pulse dose rate brachytherapy (20–25 h pulses, 1 Gy/pulse at point ‘A’). Oxygenation data are given as median pO 2 of pooled readings and percentage of readings below 5 mm Hg (HF 5). Results: Median pO 2 values ranged from 0 to 60 mm Hg (median 10). HF5 ranged from 0 to 95% (median 22%). Median follow-up was 26 months (range 9–54 months). Actuarial overall and disease-free survival rates (OS/DFS) at 3 years were 53%/50%. Comparing patients with median pO 2 ≤10 mm Hg ( n=26) to patients with higher median pO 2 levels ( n=25) calculated DFS was 34 and 69%, respectively ( P<0.02). Corresponding data for local control were 47 and 84% ( P=0.053). Comparing patients with HF5 below and above the median calculated DFS was 36 and 66%, respectively ( P<0.02). Patients who had median pO 2 <10 mm Hg and HF5 >20% had the worst prognosis (3-year DFS: 28%). Besides oxygenation status, stage and initial hemoglobin concentration were statistically significant for treatment outcome. Conclusions: This study confirms earlier data that the presence of hypoxia is associated with poor local control and survival in patients with carcinoma of the uterine cervix. Polarographic pO 2 measurements are feasible under routine conditions and can be regarded as a reproducible predictive assay.