Five-year trends of bone scan and prostate-specific membrane antigen positron emission tomography utilization in prostate cancer: A retrospective review in a private centre.

INTRODUCTION: In the last 5 years, there has been a significant focus on the use of positron emission tomography (PET) for primary and secondary staging of prostate cancer. In this study, we aim to describe the trends of use between Gallium-68 prostate-specific membrane antigen ligand (Ga-68 PSMA) PET/computed tomography (PSMA PET/CT) and nuclear medicine bone scan (NMBS) for prostate cancer staging in the first institution in Australia to offer both modalities.

METHODS: We evaluated trends in prostate cancer staging/restaging imaging modalities at our facility between the time period January 2013-April 2018. Imaging logs were filtered to identify NMBS and PSMA PET/CT scans done within the time period for prostate cancer. Sub-analysis was undertaken (i) to investigate the number of patients who were imaged using both modalities, (ii) to compare the age of the patients in the NMBS group and the PSMA PET/CT group and (iii) to compare the use of PSMA PET/CT for pre-treatment staging compared to the detection of recurrence or metastatic disease (secondary staging).

RESULTS: A total of 3144 examinations were performed in the time period reviewed, with 546 NMBS and 2598 PSMA PET/CT scans performed. In the 6 months after PSMA PET/CT was introduced, there was a 45.7% decrease in the number of NMBS performed and 95.3% decrease across the duration of the study. In the PSMA PET/CT cohort, 1569 examinations were performed for pre-treatment staging and 1029 performed for secondary staging. There was a significant difference in the proportion of PSMA PET/CT conducted for pre-treatment staging compared with secondary staging when comparing the first and final 500 examinations (P < 0.05).

CONCLUSION: After the introduction of PSMA PET/CT there was a marked decline in the use of NMBS for prostate cancer staging. This finding is of note as it occurred before there was clinical data or guidelines supporting the use of PSMA PET/CT for prostate cancer imaging.