CHAPEL HILL, N.C. — Prostate cancer can be difficult to treat with radiation, because the prostate gland is about the size of a walnut.
And it can move, just enough for radiation treatments to miss it and possibly damage healthy tissue.
Dr. Joel Tepper, a radiation oncologist at the University of North Carolina at Chapel Hill’s Lineberger Comprehensive Cancer Center, believes the Calypso System is the answer to the long-standing problem of external beam radiation treatment of prostate cancer.
"It gives us a much higher confidence that we are treating precisely the areas that we need to treat," he said.
The problem has been that the prostate can move, ever so slightly, for several reasons, including how much air or stool is in the rectum and how much urine is in the bladder.
The Calypso System works much like a global positioning satellite. Three tiny transponder seeds, each the size of a grain of rice, are placed inside the prostate.
A flat plate placed above the patient relays a signal from the seeds to cameras, tracking the exact position of the prostate on a second-by-second basis.
"And then, if it's moving outside the bounds that we have previously accounted for, we can stop the treatment and reposition the patient so that we have the appropriate level of accuracy," Tepper said.
The Calypso System is one of several treatment options for prostate cancer.
Many men choose to have the entire prostate surgically removed, but that comes with certain risks such as impotency. Another option, called brachytherapy, leaves radiation seeds inside the gland.
According to a study by the American Society of Oncologists, most patients tend to choose the treatment offered by the first specialist they see, whereas other treatment options might work just as well or even better for that patient.
More medical centers, like Lineberger, have a multidisciplinary approach, having patients meet with different specialists – a urologist, a medical oncologist, a radiation oncologist – who form a consensus on the best approach for each patient.
But doctors say options are limited if men don't catch prostate problems early through recommended screening – a digital rectal exam and a PSA blood test for men over age 40.