According to a new study from the University of California Los Angeles,earlier identification of the location of prostate cancer recurrence after radical prostatectomy could help guide salvage radiotherapy. The study published in Nuclear Medicineutilizes PET/CT with gallium-68 prostate-specific membrane antigen (68Ga-PSMA-11) to locate the cancer recurrence location.Prostate cancer biochemical recurrence occurs in 20% to 80%of patients within 10 years after radical prostatectomy and is difficult to treat. Salvage radiotherapy is the main option for treatment, but the imaging modalities currently used are not sensitive enough to identify the location of recurrence until it is too late, leading to a “best-guess” approach for targeting the radiotherapy.
The study included 270 well-documented patients from databases established at four institutions (UCLA and three in Germany: Technical University of Munich, Ludwig-Maximilians-University of Munich, and University of Essen). All patients had a biochemical recurrence of prostate cancer after radical prostatectomy but had not received prior radiotherapy. They underwent PSMA PET/CT at a serum PSA level of less than 1 ng/ml.
Nearly half (132 patients or 49 percent) had a positive PSMA PET/CT, and 52 (19 percent) had at least one PSMA-positive lesion that was not covered by the consensus clinical target volume (CTV). The two most common PSMA PET-positive lesion locations outside the consensus radiation fields were bone (23/52, 44 percent) and perirectal lymph nodes (16/52, 31 percent).
According to the study, salvage radiotherapy is the only remedial therapy, if the recurrent disease is completely encompassed by the radiotherapy fields. Visualizing sites of prostate cancer recurrence accurately, at an early stage, enables true precision radiation therapy.