PSMA PET, CT detects recurrent prostate cancer early, guides radiotherapy

Nuclear imaging may better locate recurrent prostate cancer after prostatectomy, and aid in earlier detection after recurrence all while simultaneously providing the sensitive imaging needed to guide salvage radiotherapy in patients, according to a study in the February issue of The Journal of Nuclear Medicine.

University of California, Los Angeles (UCLA) researchers used PET and CT with gallium-68 prostate-specific membrane antigen (68Ga-PSMA-11) in 270 well-documented patients. Patient data were taken from databases at four institutions (UCLA and three in Germany: Technical University of Munich, Ludwig-Maximilians-University of Munich and University of Essen).

These patients all had a biochemical recurrence of prostate cancer after radical prostatectomy, but no prior radiotherapy. They were given PSMA PET/CT at a serum PSA level of less than 1ng/ml.

A total of 132 patients (49 percent) had a positive PSMA PET/CT, and 52 (19 percent) had at least one PSMA-positive finding not covered by the consensus clinical target volume (CTV).

"Based on European data, we believe that PSMA PET/CT, an imaging technique that is not yet approved by the U.S. Food and Drug Administration, is sufficiently sensitive to detect and localize the recurrent prostate cancer early enough to potentially guide salvage radiotherapy," said Jeremie Calais, MD at UCLA in a Society of Nuclear Medicine and Molecular Imaging press release. "The first sign of prostate cancer recurrence is a rising PSA. For salvage radiotherapy to be successful, it should be initiated before the PSA rises above 1 ng/mL, and ideally, closer to 0.2 ng/mL or lower."

Salvage radiotherapy is only effective if the recurrent cancer is completely within the radiotherapy fields. Therefore, these findings would have helped nearly 20 percent of the patients in this study, Calais and colleagues note. The treatment holds promise for the future of targeted therapy and precision medicine which the field is striving to move toward.

"Visualizing sites of prostate cancer recurrence accurately, and early enough to guide therapy, enables truly precision radiation therapy. This is, in fact, the definition of individualized medicine. We believe that PSMA PET/CT imaging will ultimately be incorporated into the standard of care for prostate cancer patients with biochemical recurrence,” Calais said in the release.