Purpose: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center. Methods: Study cohort included 963 consecutive patients with newly diagnosed PCa referred Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria, and PSA levels.Results: Bone metastases were found in 188 (19.5%) of 963 patients. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). Slightly more than half of them (54.1%) had "pure" osteoblastic lesions, while the other 45.9% had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were "pure" intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were "pure" osteolytic lesions. Bone metastases were found in 10.7% of patients with PSA<10 ng/dL and in 27.4% of patients with PSA>10 ng/dL; in 6.1% of patients with GG≤2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease. Conclusion: Although traditionally bone metastases of PCa are considered osteoblastic; osteolytic and intramedullary metastases are common, as identi ed on PET with labeled-PSMA.

Purpose: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center.Methods: Study cohort included 963 consecutive patients with newly diagnosed PCa referred Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria, and PSA levels.Results: Bone metastases were found in 188 (19.5%) of 963 patients. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). Slightly more than half of them (54.1%) had "pure" osteoblastic lesions, while the other 45.9% had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were "pure" intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were "pure" osteolytic lesions. Bone metastases were found in 10.7% of patients with PSA<10 ng/dL and in 27.4% of patients with PSA>10 ng/dL; in 6.1% of patients with GG≤2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease.Conclusion: Although traditionally bone metastases of PCa are considered osteoblastic; osteolytic and intramedullary metastases are common, as identified on PET with labeled-PSMA.