It’s common knowledge among cancer researchers that tumors lacking oxygen (hypoxic) don’t respond well to radiation. Flint Animal Cancer Center radiation oncology section head, Dr. Susan LaRue, is working with colleagues at four universities to test a new approach that adds oxygen to tumors with the help of microbubbles.

“Solid tumors, whether in pets or people, are characterized by disorganized, leaky vessels that promote regions of low oxygenation. Unfortunately, the effectiveness of many of our cancer therapies also substantially decreases when tissue has less oxygen,” said Paul Dayton, Ph.D., University of North Carolina, Chapel Hill, and North Carolina State University, the study’s principal investigator. “In recent laboratory analysis, we have had success in using microbubbles to increase tumor oxygen levels. Based on this data, we’re ready for the next steps, and I’m excited to work with Dr. LaRue and others to evaluate this therapy in dogs with cancer.”


The project, called Treating Tumoral Hypoxia via Ultra­sound-Guided Oxygen Release for Improving Radiation Therapy, is funded by the National Institutes of Health. The study is enrolling canine patients with soft tissue sarcomas, a cancer of the connective tissue. These canine tumors are bulky and often radiation-resistant, with evidence of tumor hypoxia.

Per the protocol, microbub­bles are injected into patients in the treatment group. (Control group patients will receive stan­dard radiation therapy.) Then, using a handheld ultrasound device, technicians guide the bubbles to the tumor. The fragile microbubbles break and release oxygen into the tumor tissue. Immediately following, the tu­mor is treated with radiation.

If proven effective, the micro­bubble application paired with radiation could translate to any hypoxic tumor, whether in dogs or people, a potentially exciting breakthrough for cancer patients.


According to LaRue, the NIH- funded study provides a fruitful analysis of the microbubble appli­cation, but she saw an opportunity to learn more. Thanks to a gift from One Cure friends, Dawn and Brett Anderson, LaRue plans to biopsy the tumors before treat­ment, immediately after treatment, and three weeks post-treatment. Not only will the team be able to measure changes to the tumor size, but they will also be able to analyze radiation-induced tumor DNA changes at different points in time.

“This study is a win-win,” said LaRue. “The microbubble study can inform future treatment for all cancer patients, while the tumor biopsies provide us with genetic information about soft tissue sarcomas that can lead to a new understanding of this disease. We have lots of possibilities.”