Nuclear imaging technique could detect early recurrent prostate cancer

A nuclear imaging technique could detect recurrences of prostate cancer before routine testing, allowing clinicians and patients the chance to tackle metastasis before it becomes life-threatening, according to research out of the University of California, Los Angeles.

Biochemical recurrence of prostate cancer is common, lead author Jeremie Calais, MD, and colleagues wrote in the Journal of Nuclear Medicine—in between 20 and 80 percent of global cases, metastases present themselves within a decade after a patient undergoes radical prostatectomy.

“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,” Calais said in a release from the Society of Nuclear Medicine and Molecular Imaging.

Salvage radiotherapy is the standard of treatment—and, often, the only option—when dealing with prostate cancer reappearances, but the imaging modalities currently available are too low-quality to detect recurrences before it’s too late, the study stated. And oncologists have to act quickly if they suspect metastasis, since radiotherapy is most successful when a patient’s prostate-specific antigen (PSA) scores are below 1 ng/mL.

“The first sign of prostate cancer recurrence is a rising PSA,” Calais said. “For salvage radiotherapy to be successful, it should be initiated before the PSA rises about 1 ng/mL, and ideally, closer to 0.2 ng/mL or lower.”

Calais’ team evaluated data from 270 patients admitted to hospitals at either UCLA or in Germany. They underwent the experimental PSMA PET/CT test, and nearly half recorded a positive result.

Salvage radiotherapy is only curative if metastatic disease is encompassed by radiotherapy fields, Calais and co-authors said, so in almost one-fifth of the study population, PSMA PET/CT results could have had a “potentially major impact” on how the patients would react to radiotherapy.

Nineteen percent of patients showed at least one PSMA-positive lesion that wasn’t covered by the consensus clinical target volume, the authors reported. In 44 percent of cases, PSMA PET-positive lesion locations outside of consensus radiation fields were either bone or perirectal lymph nodes.

“Visualizing sites of prostate cancer recurrence accurately, and early enough to guide therapy, enables truly precise radiation therapy,” Calais said. “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.”