Ultrasound-guided pO₂ measurement in breast cancer patients before and after hyperthermia treatment

The significance of tumor hypoxia extends beyond conventional radiation resistance. It has been found that tumor hypoxia affects drug resistance, angiognesis, cytokine production, cell cycle control, apoptosis and development of distant metastases. Recently, it has been reported that hyperthermia improves tumor oxygenation in both canine as well as human soft tissue sarcoma. This study describes a new optimized technique for pO₂ measurement in breast cancer patients using ultrasound-guided placement of Eppendorf polarographic oxygen probes. Locally advanced breast cancer patients, participating in a phaseI/II study of neoadjuvant liposomal doxorubicin/paclitaxel/hyperthermia treatment, were the subjects of this study. Tumor oxygenation was measured before and 24 h after hyperthermia treatment.Advantages of the ultrasound-guided pO₂ probe placement are the following: accuracy with visualization and verification of the Eppendorf electrode placement in tumor tissue; monitoring of the electrode movement through the tumor tissue during the measurement; ability to avoid electrode placement near or in large blood vessels by using color Doppler imaging; and spatial reproducibility of the second measurement. Despite progress in the technology that can be used to measure tumor hypoxia, accurate and verifiable placement of the oxygen probes in tumor tissue is of tremendous importance. Ultrasound-guided pO₂ probe placement should become standard technique to improve accuracy and reliability in the assessment of tumor oxygenation for disease sites in which it is appropriate.

Supported by a grant from the NIH CA42745.