MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The only curative treatment for recurrent prostate cancer after radical prostatectomy is salvage radiotherapy. Unfortunately, current standard imaging modalities are too insensitive to visualize the location of the recurrence until it is too late. As a result, salvage radiotherapy is directed to areas only suspected to harbor the recurrence based upon a “best guess” approach according to standard guidelines that define radiotherapy treatment volumes.
PSMA PET/CT is a new imaging technique with sensitivity sufficient to detect and localize the recurrent prostate cancer early enough to potentially guide salvage radiotherapy.
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. PSMA PET/CT localizes sites of prostate cancer recurrence in up to 70% of patients with low PSA, below < 1.0.
In the US it is not yet FDA approved and currently only used for research purposes. In our current study we included 270 patients with early recurrence of prostate cancer after surgery from Germany and UCLA, we found that 20 % of the patients had at least one lesion detected by PSMA PET/CT which was NOT covered by the standard radiation fields. Obviously, salvage radiotherapy is only curative if recurrent disease is completely encompassed by the radiotherapy fields and would have failed in these patients.