Michigan Principal Investigator Daniel A. Hamstra, Ph.D., M.D., assistant professor of the Department of Radiation Oncology and 10 co-researchers are currently conducting the first multi-institutional study, evaluating a new form of radiation treatment for prostate cancer coupled with sophisticated real-time tumor tracking, at the University of Michigan Health System in Ann Arbor.

The team evaluates the safety of shortened (hypfractionated) stereotactic body radiation therapy (SBRT) with Calypso Medical’s GPS for the body technology that is used for real-time tracking of cancerous tumors during prostate radiotherapy. The results will be compared with conventional radiation treatment.

Dr. Hamstra and his co-investigators state that SBRT increases the need for accurate, precise real-time tracking of prostate motion during radiation treatment. The administration of larger, more concentrated radiation doses raises concern, because the surrounding healthy tissue is subjected to the same high doses and therefore increases the potential for side effects, such as rectal injury, impotence and difficulty urinating.

The Calypso Medical’s real-time tracking technology accurately pinpoints the precise location of the prostate, allowing doctors to administer larger doses of SBRT with more confidence, whilst lowering the total amount of treatments.

Prof. Hamstra states:

“To a large extent, identification of prostate location has only been performed prior to the start of treatment without taking into account the motion of the prostate during treatment, yet precise targeting of the prostate gland during radiation is critically important in order to avoid delivering unintended radiation to healthy tissue.

This is the first multi-institutional study to incorporate use of the Calypso real-time tumor tracking technology, which allows us to significantly reduce the margin of healthy tissue around the prostate to prevent the development of unwelcome side effects. We are optimistic that use of the Calypso System in concert with a small number of dose-intensified treatment sessions may be a way to optimize SBRT.”

The multi-site study will be testing whether a short-course, treatment plan with continuous real-time evaluation of prostate motion is safe and effective for patients compared to conventional treatment.

The Phase II study will be held over a 39-month period with 66 patients who will each receive five 30-minute treatment sessions (fractions) with a resting period of at least two days between each fraction. Each fraction size will consist of 7.4 units of absorbed radiation dose (Gray) with a total dosage of 37 Gray. The five-fraction treatment period will last between 15-19 calendar days compared to a conventional treatment of 40-45 daily treatments spread over an eight to nine week period.

Dale Litzenberg, Ph.D., co-investigator and clinical assistant professor, from the Department of Radiation Oncology at the University of Michigan said:

“The Calypso technology is critical because it provides the only real-time means to localize the prostate, providing needed information regarding motion that occurs due to normal bladder and bowel filling. With this information, we can use tighter treatment margins, which should lessen the risk for both acute and late toxicities. Combining Calypso with SBRT creates a treatment approach that allows patients to maintain their quality of life while spending significantly less time away from family and work.”

Participating institutions working in conjunction with the University of Michigan include Washington University (St. Louis, Mo.); The Fox Chase Cancer Center (Philadelphia); Cedars Sinai Medical Center (Los Angeles), and Radiation Oncology Centers (Sacramento, Calif.).

Lisa Levine, Ph.D., vice president, clinical and pre-market regulatory affairs for Calypso Medical said:

“We are very encouraged by this multi-institutional study evaluating Calypso’s real-time tumor tracking for prostate SBRT, as this research will offer broad-based information to complement previous single-center studies with the same objectives. Recent results from a single-center study reported favorable toxicity and quality-of-life outcomes in urinary, rectal and sexual function. [1] These study results and others suggest that the much shorter delivery schedule combined with the potential for a more efficacious treatment makes SBRT a very appealing option for the right patient.”

Calypso Medical will be highlighting the use of real-time tracking during prostate cancer radiotherapy and investigational use in lung cancer at the upcoming 2011 Joint American Association of Physicists in Medicine (AAPM) and the Canadian Organization of medical Physicists (COMP) meeting, July 31-August 4 at the Vancouver Convention Centre (Booth #1131).

Petra Rattue