To assess the role of 68Gallium-labeled-prostate-specific membrane antigen PET/CT (68Ga-PSMA-PET/CT) in risk group definition and radiotherapy planning in the initially planned definitive radiotherapy (RT) for prostate cancer patients.
The clinical data of 191 prostate cancer patients treated with definitive intensity-modulated RT were retrospectively analyzed. All patients were initially staged with thoracoabdominal CT and bone scintigraphy, and the second staging was performed using 68Ga-PSMA-PET/CT. Both stages were evaluated for the decision making of RT and any change in RT target volumes.
After staging with 68Ga-PSMA-PET/CT, 26 patients (13.6%) had risk group changes, 16 patients (8.4%) had an increase in risk group, and 10 patients (5.2%) had a decrease in risk group. Down-staging occurred in 22 patients (11.5%), and upstaging was observed in 30 patients (15.7%). A total of 26 patients (13.6%) had nodal stage changes. After the 68Ga-PSMA-PET/CT scans, the number of metastatic patient increased to 17 (8.9%), with 4 of them moving from oligo- to polymetastatic disease. An additional irradiation of pelvic lymphatics and metastatic site was performed in 13 patients (6.8%) and 6 patients (3.2%), respectively. The RT was aborted in 4 patients (2.1%) because of parenchymal or distant site metastasis observed in the 68Ga-PSMA-PET/CT.
We found that 68Ga-PSMA-PET/CT causes considerable migration in stage, risk group, and RT field arrangements, especially in high-risk patients regardless of the GS and baseline prostate-specific antigen values alone. 68Ga-PSMA-PET/CT seems to have a great influence on RT decision making in prostate cancer patients.
From the Departments of *Radiation Oncology
†Nuclear Medicine, Başkent University Faculty of Medicine, Adana Dr Turgut Noyan Research and Treatment Center, Adana
Departments of ‡Radiation Oncology
§Nuclear Medicine, Hacettepe University Faculty of Medicine, Ankara, Turkey.
Received for publication April 26, 2019; revision accepted May 19, 2019.
Conflicts of interest and sources of funding: none declared. The authors are responsible for the content and writing of the manuscript.
Correspondence to: Cem Onal, MD, Department of Radiation Oncology, Baskent University Faculty of Medicine, Adana Dr Turgut Noyan Research and Treatment Center, 01120 Adana, Turkey. E-mail: email@example.com.
Online date: July 8, 2019