ASCO PROSTATE: Imaging Agent Helps Pinpoint Margins of Prostate Cancers

KISSIMMEE, Fla., Feb. 26 -- Fusion imaging with the capromab pendetide (ProstaScint) imaging agent allows for visualization of the boundaries of the malignant tissue in the prostate and more precise placement of radioactive seeds for brachytherapy, investigators reported here.

That increased accuracy was associated with a 91.7% prostate cancer survival at eight years, said radiation oncologist Rodney Ellis, M.D., of Case Western Reserve University in Cleveland, and Aultman Hospital in Canton, Ohio, in a poster presentation at a prostate cancer symposium here.

Dr. Ellis reported that when the fusion image created by use of computer-assisted tomography and single-photon emission computed tomography and capromab pendetide was used, clinicians were able to see exact boundaries of the lesion, which helped them limit brachytherapy damage to healthy tissue.

The study included 236 patients in whom SPECT/CT capromab pendetide therapy was used to detail 203 lesions that were completely contained within the prostate. In those patients, the eight-year, disease-free survival rate was 91.7%.

In 11 patients in whom the image showed cancer around the edges of the prostate, the eight-year survival was 72.7%, he said.

In 22 patients, imaging revealed cancer that was clearly outside the prostate. For those patients survival dipped to 66.7%, he said, indicating that the imaging technology can differentiate between those patients who are clearly going to be helped by brachytherapy and those who will need additional treatment.

"If we see that the cancer is already outside the capsule of the prostate, then we can order external-beam radiation or hormonal treatments to supplement the brachytherapy procedure," Dr. Ellis said.

"This study showed the value of functional imaging in prostate cancer," he said. "He predicted that the studies will prompt doctors to take another look at the procedure," Dr. Ellis said.

"Doctors have not taken to ProstaScint even though it has been an approved agent for many years," commented Cleveland Clinic urologist Eric Klein, M.D. But he said that further studies confirming its ability to locate cancers more easily make clinicians more willing to use it to guide treatment.

Dr. Ellis receives honoraria and research funding from Cytogen Inc., Princeton, N.J., which makes ProstaScint. Dr. Klein listed no conflicts of interest, but he was lead investigator of small ProstaScint study reported at the American Urological Association meeting in 1997.