Tracking technology reduces side effects from radiation

The Calypso System (Calypso Medical Technologies, Inc., Seattle) offers a significant reduction in rectal and urinary treatment-related side effects during high-dose external beam radiation for prostate cancer, recent study findings show.

"This is the first comparative study to show that margin reduction in prostate cancer radiation therapy has clinically significant and measurable benefits in decreasing acute toxicity and short-term side effects," said lead author Constantine Mantz, MD, a radiation oncologist at 21st Century Oncology in Cape Coral, FL. "By reducing acute toxicity, we hope these patients may also experience a significant reduction of long-term side effects."

Researchers compared the current impact of margin reduction (AIM) study group of 64 patients to 153 patients in a comparator study published in the New England Journal of Medicine (2008; 358:1250-61). Beacon electromagnetic transponders were implanted into the prostates of the AIM study group. This level of precision allowed researchers to reduce the planning target volume (PTV) margin while at the same time increase the radiation dose to 81 Gy to more effectively treat the cancer. Comparator patients were treated using standard institutional processes and larger PTV margins.

In both groups, patient-reported quality of life was assessed before and after the completion of radiation therapy. The AIM study group experienced significantly fewer side effects associated with bowel urgency and frequency, fecal incontinence, and urinary irritation than the comparator group. AIM patients not receiving hormonal therapy also experienced smaller, yet statistically significant advantages over the comparator group in terms of sexual function.

"Without any tracking at all, I used to use a 10 mm treatment margin," said Howard M. Sandler, MD, of Cedars-Sinai Medical Center, Los Angeles, lead author on the AIM study, and co-author of the New England Journal comparator study. "With Calypso, I use a 3-mm treatment margin, and the AIM study results demonstrate an improvement in patient-reported quality of life. Of all the technologies that are available, the Calypso System is the only one that can do real-time tracking as well as localization and provides an important advantage in terms of keeping the radiation beam on the prostate."

Findings from the study were published online in Urology (Feb. 12, 2010). The study was supported by Calypso Medical Technologies.