IMPACT ON RADIOTERAPIC TREATMENT VOLUMES CHANGES IN PROSTATE CANCER PATIENTS WITH THE USE OF PET/TC PSMA-68GA IN THE ADJUVANT AND SALVAGE SCENARIO

Introduction: With still limited access and a poorly established role in the scenario of prostate cancer (PCa) with biochemical failure after radical prostatectomy (PR), PET/TC PSMA-68Ga has been increasingly used by urologists, oncologists and radiation -oncologist as a pre-treatment staging tool for radiotherapy (RT) and / or systemic therapy in this setting. The studies available so far, mostly case series or phase II, do not show survival impact, but show rates of up to 40% change in radiotherapy treatment volume when PSMA-68Ga PET / CT fusion with simulation CT for RT is used as a contour guide and all hipermetabolic areas are included, comparing with standard CTV based on international guidelines Objectives: We evaluated the impact of using the PSMA-68Ga PET / TC on changing the clinical target volume (CTV) contour volumes of patients who have undergone salvage / adjuvant RT at a single brazilian private cancer center since its implantation in 2015 Methods: Retrospective analysis of the registry of patients undergoing salvage / adjuvant RT was performed, and those who had the fusion of PET/CT PSMA-68Ga with the planning CT used for adequacy of CTV delineation in RT treatments were selected. 4 years. All patients underwent intensity modulated RT (IMRT) with the last fraction received at least 6 months from the start of data collection. Treatment volumes were analyzed and compared with the standard RTOG-defined volume. It was also assessed whether there was a greater tendency for dose escalation in the PSMA-68Ga hypercaptation regions Results: A total of 201 patients, mean age 68.4 years, mean pre-treatment PSA of 1.22 ng/dl underwent adjuvant / salvage RT during the study period, of which 27.6% underwent PET / CT PSMA-68Ga up to 4 weeks before RT. Of these, 10.5% had different treatment volumes from the guideline RTOG limits and 12.9% received a dose boost in the PSMA-68Ga hypercaptation region Conclusion: The use of PSMA-68Ga PET/CT ensures better accuracy in delineating radiotherapy treatment volumes in the context of PCa adjuvancy and salvage, as well as facilitates dose escalation in suspected relapse areas, which may result in a better biochemical control.

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Artikel online veröffentlicht:
23. Oktober 2019