Prostate-specific membrane antigen (PSMA) PET/CT scans can help identify prostate cancer patients with rising levels of prostate-specific antigen (PSA) after radical prostatectomy who can most benefit from salvage radiation treatment, according to a study published in the December issue of the Journal of Nuclear Medicine.
Australian researchers took a somewhat novel approach by investigating whether the use of PSMA PET/CT affected patient response to treatment, not just whether PET scans resulted in a change in management.
"In the study, these patients underwent imaging with a PSMA-PET scan and had treatment based on the results of the scan findings," said co-author Dr. Louise Emmett from St. Vincent's Hospital in Sydney. "The study then followed how these men were treated, and whether the treatment was effective."
The researchers analyzed 146 men; 99 patients received salvage radiation treatment, with an overall treatment response after salvage radiation of 72%. Among the negative-PSMA patients, 44% (27 of 60) had salvage radiation treatment (JNM, December 2017, Vol. 58:12, pp. 1972-1976).
The negative-PSMA patients who received salvage radiation treatment had an 85% treatment response; meanwhile, 65% of the negative-PSMA patients who did not receive salvage radiation treatment experienced increases in prostate-specific antigen.
For individuals with disease confined to the prostate fossa, 83% responded to salvage radiation treatment. For men with nodal disease, 61% had a treatment response following salvage radiation treatment.
"The results of the study show that PSMA PET is more predictive of a treatment response than PSA level, surgical margins, or seminal vesicle involvement," Emmett said. "In addition, men with a negative PSMA-PET scan were the most likely to respond to salvage radiotherapy with a significant treatment response."