(UroToday.com) The 2023 ESMO annual meeting included a session on management of (very) high-risk localized prostate cancer, featuring a presentation by Dr. Karolien Goffin discussing usefulness and limitations of PSMA imaging/PET in high-risk localized disease. Dr. Goffin started her presentation by emphasizing that there are several key points to keep in mind when considering PSMA PET in high-risk localized disease, including: (i) sensitivity, (ii) specificity, (iii) impact, (iv) outcome (v) patient comfort, (vi) cost, and (vii) mSv
Dr. Goffin highlighted the proPSMA trial, which was a multi-center, two-arm randomized controlled trial of men with histologically confirmed prostate cancer who were being considered for curative intent radical prostatectomy or radiotherapy.1 With regards to the primary outcome, PSMA PET/CT had a 27% absolute greater AUC for accuracy compared to conventional imaging (95% CI for difference: 23 – 31%): 92% (95% CI: 88 – 95%) vs. 65% (95% CI: 60 – 69%):
When discussing staging of lymph nodes in men with high risk localized disease, Dr. Goffin notes that the sensitivity of PSMA PET/CT ranges from 33%-92% and specificity per lesion ranges from 69%-98%:
One of the limitations of PSMA PET/CT can be false positive bone lesions, particularly in the area of the ribs. Of note, the problem of unspecific bone lesions is mainly present with 18F-PSMA-1007.
The proPSMA does give us some data on the impact of management, with imaging findings leading to change in management (treatment intent, modality, or delivery) in 28% of men in the PSMA PET/CT arm versus 15% of men in the conventional imaging arm. Following first-line PSMA PET/CT, 20 (14%) of 148 patients were directed from curative to palliative-intent treatment, 11 (7%) had a change in radiotherapy technique, and 11 (7%) in surgical technique. Notably, conventional imaging was associated with a higher radiation dose (19.2 mSv compared to 8.4 mSv; absolute difference 10.9 mSv, 95% CI for difference: 9.8 – 12.0 mSv).
Dr. Goffin notes that there is some data suggesting that PSMA PET/CT staging does improve outcomes. In a retrospective study from Ferraro et al.2 they assessed staging in 105 patients planned for radical prostatectomy, including 53 with conventional imaging and 52 with PSMA PET/CT. The rate of free surgical margins and PSA persistence after surgery was 64% and 17% for the conventional imaging group and 77% and 6% for the PSMA group (p = 0.15 and 0.13, respectively). Subgroup analysis with high-risk patients revealed PSA persistence in 7% (3/44) in the PSMA group and 25% (7/28) in the CI group (p = 0.04):
Patients also like having a PSMA PET/CT rather than conventional imaging. In the proPSMA trial, patients described a PSMA PET/CT as a “1-stop shop”, as well as having decreased radiation exposure:
Finally, there is evidence that PSMA PET/CT is more cost effective than conventional imaging. An ad hoc cost-effectiveness analysis from the proPSMA trial demonstrated that routine use of 68Ga-PSMA-11 PET/CT in this setting saved AUD$959 per additional accurate detection of nodal disease and AUD $1,412 per additional accurate detection of distant metastases.3 However, it bears note that the cost of 68Ga-PSMA-11 PET/CT at the time of report publication was AUD $1,203 compared to AUD$ 1,412 for conventional imaging. Given that the average cost of a PET scan in the United States is USD $5,438, the results of this cost-effectiveness analysis may not be translatable to different healthcare systems:
Dr. Goffin concluded her presentation discussing usefulness and limitations of PSMA imaging/PET in high-risk localized disease by highlighting that indeed, PSMA PET in high risk localized disease does check all the boxes:
Presented by: Karolien Goffin, MD, PhD, University Hospital Leuven, Leuven, Belgium
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2023 European Society of Medical Oncology (ESMO) Annual Meeting, Madrid, Spain, Fri, Oct 20 – Tues, Oct 24, 2023.
References:- Hofman MS, Lawrentschuk N, Francis, RJ, et al. Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): A prospective, randomized, multicentre study. Lancet 2020 Apr 11;395(10231):1208-1216.
- Ferraro DA, Lehner F, Becker AS, et al. Improved oncological outcome after radical prostatectomy in patients staged with 68Ga-PSMA-11 PET: A single-center retrospective cohort comparison. Eur J Nucl Med Mol Imaging. 2021 Apr;48(4):1219-1228.
- De Feria Cardet RE, Hofman MS, Segard T, et a. Is Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Imaging Cost-effective in Prostate Cancer: An Analysis Informed by the proPSMA Trial. Eur Urol. 2021;79(3):413-8.