A satellite-based navigation system originally intended for military applications, but made available for civilian use in the 1980s is increasingly showing up in vehicles, cell phones, sports watches and even on implantable microchips designed to reunite lost dogs with their owners.

Now, FDA has cleared a GPS-like system for tracking the movement of cancerous tissue during radiation therapy for prostatectomy patients.

Calypso Medical (Seattle) said the regulatory agency cleared a new indication for the use of implantable Beacon electromagnetic transponders with the Calypso 4D Localization System – often referred to as "GPS for the Body" – in external-beam radiation therapy. Previously, the technology was only cleared for patients with an intact prostate, the company said.

"Extending the clinical use of the Calypso system is vital for post-prostatectomy patients at risk or diagnosed with recurrent prostate cancer," said Eric Meier, the company's president/CEO. "Clinicians gain increased confidence when treating these patients. This new indication broadens the spectrum of prostate cancer patients who will benefit from continuous target tracking during radiation therapy."

Meier told Medical Device Daily that up to 20% of patients who have their prostate removed are later diagnosed with recurrent prostate cancer and need radiation therapy. Because radiation is not selective, he said, it is important to know exactly where the tumor is so as to avoid nearby organs and healthy tissue.

FDA cleared the 4D Localization System in July 2006. It consists of five components that work together: the electromagnetic positioning transponders which are about the size of a grain of rice, a console the size of a large rolling suitcase, and electromagnetic array to receive the transponder signals, a tracking workstation and infrared cameras installed in the treatment room.

The technology is designed to track any movement of the cancer in real time and alert the technician if the targeted tissue moves beyond pre-determined parameters so they can adjust the external beam of radiation, according to Calypso. There also is the potential for using higher doses of radiation to attack tumors while reducing the procedure time, according to Ken Russell, MD, a radiation oncology clinical chief at the Seattle Cancer Care Alliance and the University of Washington (UW; Seattle).

"The purpose of radiation oncology is to accurately deliver the treatment to the cancer and avoid as much as possible the normal nearby organs," said Russell in a statement Calypso released earlier this year. He is also vice chairman of the UW's Department of Radiation Oncology.

Meier also told MDD that the company sees this latest FDA clearance as a step towards additional indications for the system, including breast and lung cancer. He added that the technology was all developed in-house at Calypso, which is a privately held company incubated by Frazier Healthcare and founded a little more than eight years ago.

The advantage of using "GPS for the Body," the company says, is that the radiation dose stays on target and less of it reaches surrounding healthy tissue.

Calypso says its technology addresses two major issues in modern radiation oncology: errors in treatment set-up and tumor motion during treatment.

"Patients with high Gleason scores, extracapsular extension, positive surgical margins or seminal vesicle involvement are at risk of developing biochemical failure following radical prostatectomy," said David Lee, MD, a University of Pennsylvania (Philadelphia) urologist. "These patients often need adjuvant radiation therapy. Having the benefit of continuous real-time tracking during radiation therapy is critical to minimizing possible complications associated with external beam radiation therapy. It is imperative to know precisely where the prostatic bed is located during radiation treatment. The objective tracking data, provided by the Calypso system, may be the key to achieving the desired outcomes for these aggressive cases."

The company reported raising $42.2 million in Series D private equity financing last year.

Calypso's technology also got a mention last fall during a physician panel on prostate cancer at the Piper Jaffray (Minneapolis) Healthcare Conference in New York. Jeffrey Forman, MD, medical director for seven Michigan clinics in the nationwide 21st Century Oncology chain, cited the 4D Localization System, calling it "really cool technology".