New Insights in the Detection and Staging of Prostate Cancer

Abstract

Prostate cancer (PCa) is a prevalent malignancy with a significant gap between its incidence and mortality rates, indicating that not all forms are life-threatening. The disease ranges from indolent to aggressive types, making accurate detection and staging vital for effective treatment. This thesis explores recent advancements in imaging techniques that have improved the precision in detecting and staging clinically significant prostate cancer (csPCa), aiming to enhance patient outcomes while minimizing unnecessary interventions. Part I of the thesis focuses on the role of Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) in detecting and characterising PCa. Chapter 2 investigates the effectiveness of the 18F-PSMA-1007 tracer for identifying intraprostatic PCa. The study finds significant correlations between the maximum standardised uptake value (SUVmax) on PET/CT scans and both the International Society of Urologic Pathology (ISUP) Grade Group (GG) and the PSMA Immune Reactive Score on histology, independent of tumour size. A key finding is that a SUVmax threshold of 4 captures almost all csPCa cases. In Chapter 3, the study evaluates SUVmax’s added value in predicting ISUP GG ≥ 2 and ≥ 3 on prostate biopsy, demonstrating that SUVmax significantly enhances predictive accuracy, particularly for GG ≥ 3. This suggests that high SUVmax levels could help identify patients at high risk of csPCa. In Chapter 4 the of adding PSMA PET/CT and targeted biopsy in patient recently started with active surveillance (AS) after MRI at diagnosis revealed that the number needed to scan (NNS) to detect biopsy upgrading was 11. Upgrading was more frequent in patients with negative MRI findings. Chapter 5 discusses the possibility of treating suspected PCa without histological confirmation due to the capabilities of PSMA PET/CT. The study finds that all patients with a SUVmax greater than 16 had csPCa. This raises the potential for a diagnostic pathway where prostatectomy could be performed without biopsy when clinical characteristics and imaging strongly suggest csPCa. Part II of the thesis addresses challenges in staging PCa, focusing on the effective use of imaging modalities. Chapter 6 validates four MRI-based nomograms for predicting side-specific extraprostatic extension (EPE). While the nomograms show fair accuracy, the Nyarangi-Dix nomogram stands out but is possibly less practical due to the extra time required for documentation. Chapter 7 demonstrates the clinical value of the Soeterik nomogram, which helped reduce positive surgical margins on the ipsilateral side of histological EPE. In Chapter 8, the thesis examines whether the cribriform pattern (CP) in prostate biopsy is an independent risk factor for metastatic disease. The study concludes that CP is not an independent risk factor, highlighting the need for further research to refine staging methods for PCa.