Oxygenation of Cervix Cancers: Impact of Clinical and Pathological Parameters

Abstract

Current knowledge on the oxygenation status of carcinomas of the uterine cervix is mostly based on pretherapeutic data obtained in pre-and postmenopausal women. Mean and median 0₂ tensions (pO₂) obtained from >20,000 p0₂-measurements in more than 400 squamous cell carcinomas of the uterine cervix observed by several research groups were, on average, distinctly lower than in normal tissues. Oxygen tensions measured in the normal cervix of nullipara patients revealed a median pO₂ of 42 mmHg, whereas in conscious patients with locally advanced cancers of the cervix (stage FIGO lb-IVa), the median pO₂ values were 10-20 mmHg. In patients under general propofol-anesthesia the median p0₂ values were 3-8 mmHg. Oxygenation status was found to be independent of various patient parameters (e.g., age, menopausal and parous state, use of oral contraceptives, smoking habits, Karnofsky index) or tumor parameters [e.g., clinical tumor size, FIGO stage, growth pattern (endophytic vs. exophytic)]². From the studies on the oxygenation status of locally advanced cervix cancers there is also clear evidence that the pO₂ distribution is extremely heterogeneous (both in space and in time) with no characteristic topological allocation of 0₂ partial pressures within the tumor (e.g., tumor center vs. tumor periphery). Furthermore, there was no clear correlation found between the tumor pO₂ and vessel length density (“vascular density”, mm/mm): Tumor regions with low vessel length density always showed low pO₂ values whereas tumor areas with higher vessel length densities can exhibit either a high or low median p0₂. Tumor-totumor variability in oxygenation is found to be greater than intra-tumor variability. In cervix cancers of moderately/severely anemic patients hypoxic areas are more frequently detected than in non-anemic (cHb > 12 g/dL) patients. Approximately 60% of cervical cancers contain hypoxic tissue areas with p0₂ values <_ 2.5 mmHg and local recurrences of cervix cancers have a higher hypoxic fraction than the primary tumors (38% vs. 25%) and lower median p0₂ values (4 mmHg vs. 10 mmHg).