Study: PSMA PET/CT Identifies 18 Percent More Metastatic Renal Cancers than Conventional Imaging

For primary staging of renal cancer, prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) may provide significant advantages over conventional imaging in detecting metastatic lesions.

For the retrospective multicenter study, recently reported in European Urology Focus, researchers compared conventional computed tomography (CT) and PSMA PET/CT in 61 patients, including 52 patients who had primary staging for suspected renal cancer.¹

(Editor’s note: This article has been adapted with permission from its original publication with our sister publication Urology Times.)

Overall, PSMA PET scans identified 195 presumed metastatic lesions in comparison to 160 with conventional imaging. PSMA PET/CT was also shown to identify more distant lymph nodes (24 vs 10), bone lesions (38 vs 19), other distant lesions (27 vs 12), and vena cava tumor propagation (8 vs 5) compared with conventional imaging.

However, conventional imaging identified more primary tumors (64 vs 59) and pulmonary lesions (69 vs 53) compared with PSMA PET/CT. The 2 modalities were similar in their detection of regional lymph nodes (49 vs 44).

“High PSMA expression allows PSMA PET imaging to identify presumed metastatic lesions that are occult on conventional imaging, which are largely size-dependent according to Response Evaluation Criteria in Solid Tumours,” wrote lead study author Arsalan Tariq, M.D., who is affiliated with the Department of Urology at the Royal Brisbane and Women’s Hospital in Brisbane, Australia, and colleagues.

The investigators also found that PSMA PET scans resulted in a change of management in 32% of patients, of which 20% (n = 13) were major changes and 12% (n = 8) were minor.

Of those patients with a major change in management, nine received surgery, two received systemic therapy, and two were placed on watchful waiting. Among those with a minor change in management, scans resulted in a change of surgical approach for five patients and the addition of a further treatment modality in three patients.

Patients who underwent a treatment modification based on PSMA PET/CT had a median progression-free survival (PFS) of 19.7 months (IQR, 17-25). Those who underwent surgery after findings on PSMA PET/CT had a median PFS of 24 months (IQR, 18-36).

Three Key Takeaways

Improved metastatic lesion detection. PSMA PET/CT demonstrated a significant advantage over conventional imaging in detecting metastatic lesions during the primary staging of renal cancer. It identified more presumed metastatic lesions, distant lymph nodes, bone lesions, other distant lesions, and vena cava tumor propagation compared to conventional imaging.
Impact on change of management. PSMA PET scans resulted in a change of management in 32% of patients. This included both major and minor changes, with major changes leading to surgery, systemic therapy, or watchful waiting. The data suggests that PSMA PET/CT can influence treatment decisions and potentially improve patient outcomes.
Potential as alternative staging modality. The study suggests that PSMA PET could be considered as an alternative staging modality at the time of primary diagnosis for renal tumors. The ability of PSMA PET to detect more metastatic lesions and influence management decisions provides a compelling rationale for its consideration in the clinical setting.

In total, 74% of those included in the study were male. The median age was 65 years. Median follow-up was 13.3 months.

Clinicopathologic and management differences between PSMA PET/CT and conventional imaging were compared. PSMA PET/CT was conducted within six weeks of initial conventional imaging.

Histopathology of the primary tumor was available for 51 patients included in the study. Most renal cancers were PSMA-avid regardless of histological subtype. Clear cell renal cell carcinoma (ccRCC) tumors more frequently had PSMA avidity compared with non-ccRCC tumors (97.5% vs 75%), but the difference did not reach statistical significance (P = .32). SUVmax was also shown to be higher for ccRCC tumors than for non-ccRCC tumors upon comparison of histological subtypes (11.0 vs 3.6; P = .12).

“Our results show that PSMA PET detected more metastatic lesions at diagnosis and could rule out possible metastases identified on conventional imaging, resulting in a management change for one-third of the cohort,” noted Tariq and colleagues. “While preliminary in nature, these data provide a compelling rationale for consideration of PSMA PET as an alternative staging modality at the time of primary diagnosis.”

1. Tariq A, Pearce A, Rhee H, et al. The role of prostate-specific membrane antigen positron emission tomography/computed tomography in primary staging of selected renal tumours: initial experience in a multicentre cohort. Eur Urol Focus. 2024:S2405-4569(23)00296-1. doi:10.1016/j.euf.2023.12.004