ESMO 2023: Usefulness and Limitations of PSMA imaging/PET in High-Risk Localized Disease
ESMO 2023, proPSMA trial, Limitations of PSMA imaging/PET, High-Risk Localized Disease in prostate cancer, PSMA cost, PSMA cost per country, PSMA/PET cost effectiveness. The 2023 ESMO annual meeting included a session on management of high-risk localized prostate cancer, featuring a presentation by Dr. Karolien Goffin discussing the usefulness and limitations of PSMA imaging/PET in high risk localized disease. She highlighted the proPSMA trial, 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. The primary outcome was that PSMA PET/CT had a 27% greater AUC for accuracy compared to conventional imaging. However, one of the limitations of the PSMAPET/CT can be false positive bone lesions, particularly in the area of the ribs. The cost of 68Ga-PSMA-11 PET/ CT at the time of report was AUD $1,203 compared to AUD$ 1,412 for conventional imaging, but this cost-effectiveness analysis may not be translatable to different healthcare systems. There is also evidence that the use of a PSMA Pet/CT in this setting saved AUD$959 per additional accurate detection of nodal disease and AUD$1,412 per additional advanced detection of distant metastases.
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(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, this is not specific per se to the radiotracer, but is seen in all available PSMA PET/CT imaging modalities:
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:
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.
• 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.