(UroToday.com) The 2024 American Urological Association (AUA) annual meeting featured a session on testicular cancer, and a presentation by Dr. Brian Hu discussing an analysis from the SEMS trial assessing the accuracy of FDG-PET scan in primary testicular seminoma. Historically, pN0 rates after primary RPLND for testicular seminoma range from 9-16% in clinical trials. However, limited prospective data exists on the accuracy of PET in Stage II testicular seminoma. Dr. Hu and colleagues utilized the SEMS trial (Surgery in Early Metastatic Seminoma) radiographic correlate to evaluate the accuracy of PET scans to detect retroperitoneal metastasis.
The SEMS trial was a phase II prospective trial evaluating the efficacy of RPLND in patients with testicular seminoma and limited retroperitoneal lymphadenopathy (diameter: 1-3 cm). Among 55 patients in the trial, the 2-year recurrence-free survival was 81%, with a 22% recurrence rate, and a 16% pN0 rate [1]. F-18 FDG PET scanning was performed as an optional study in addition to standard axial imaging prior to surgery. As follows is a representative CT and PET scan with aortocaval adenopathy with corresponding positive uptake on FDG PET:
The lymph node size, lymph node number, maximal Standardized Uptake Value (SUV), and other radiographic findings were compared with the operative report and pathology report. The interpretation of the PET scan positivity was based on local radiology from a tertiary care facility.
Among the 55 patients enrolled in the trial, 26 (47%) had a PET scan performed at a mean 22 days (range 1-90) prior to surgery. There were 20 positive PET scans (77%), with 18 of these having pathologically positive lymph nodes (PPV 90%). The mean SUV of the positive lymph nodes was 7.0 (range 2.6-18.8). In the two patients who had false positive scans, one had nodes with mild reactivity (SUV 4) and one had an avid lesion that was thought to favor metastasis but was actually the ureter. In those with positive PET scans and positive pathologic lymph nodes, PET scans accurately identified the number of positive lymph nodes only 50% of the time. Six PET scans were negative with five of these patients having confirmed pN0 disease (NPV 83%):
Dr. Hu concluded his presentation by discussing an analysis from the SEMS trial assessing the accuracy of FDG-PET scan in primary testicular seminoma with the following take-home messages:
- In patients with testicular seminoma and low-volume retroperitoneal adenopathy, PET scans may have a role in improving the accuracy of staging, though larger studies are necessary
- PET scan does not accurately determine the number of positive lymph nodes
Presented by: Brian Hu, MD, Loma Linda Urology, Loma Linda, CA
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2024 American Urological Association (AUA) Annual Meeting, San Antonio, TX, Fri, May 3 – Mon, May 6, 2024.
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