Twelve-month prostate volume reduction after MRI-guided transurethral ultrasound ablation of the prostate.

PURPOSE: To quantitatively assess 12-month prostate volume (PV) reduction based on T2-weighted MRI and immediate post-treatment contrast-enhanced MRI non-perfused volume (NPV), and to compare measurements with predictions of acute and delayed ablation volumes based on MR-thermometry (MR-t), in a central radiology review of the Phase I clinical trial of MRI-guided transurethral ultrasound ablation (TULSA) in patients with localized prostate cancer. MATERIALS AND METHODS: Treatment day MRI and 12-month follow-up MRI and biopsy were available for central radiology review in 29 of 30 patients from the published institutional review board-approved, prospective, multi-centre, single-arm Phase I clinical trial of TULSA. Viable PV at 12 months was measured as the remaining PV on T2-weighted MRI, less 12-month NPV, scaled by the fraction of fibrosis in 12-month biopsy cores. Reduction of viable PV was compared to predictions based on the fraction of the prostate covered by the MR-t derived acute thermal ablation volume (ATAV, 55°C isotherm), delayed thermal ablation volume (DTAV, 240 cumulative equivalent minutes at 43°C thermal dose isocontour) and treatment-day NPV. We also report linear and volumetric comparisons between metrics. RESULTS: After TULSA, the median 12-month reduction in viable PV was 88%. DTAV predicted a reduction of 90%. Treatment day NPV predicted only 53% volume reduction, and underestimated ATAV and DTAV by 36% and 51%. CONCLUSION: Quantitative volumetry of the TULSA phase I MR and biopsy data identifies DTAV (240 CEM43 thermal dose boundary) as a useful predictor of viable prostate tissue reduction at 12 months. Immediate post-treatment NPV underestimates tissue ablation. KEY POINTS: • MRI-guided transurethral ultrasound ablation (TULSA) achieved an 88% reduction of viable prostate tissue volume at 12 months, in excellent agreement with expectation from thermal dose calculations. • Non-perfused volume on immediate post-treatment contrast-enhanced MRI represents only 64% of the acute thermal ablation volume (ATAV), and reports only 60% (53% instead of 88% achieved) of the reduction in viable prostate tissue volume at 12 months. • MR-thermometry-based predictions of 12-month prostate volume reduction based on 240 cumulative equivalent minute thermal dose volume are in excellent agreement with reduction in viable prostate tissue volume measured on pre- and 12-month post-treatment T2w-MRI.

The current TNM staging system of renal cell carcinoma: are further improvements needed?

Objective of the study is to review the current 7th edition of the TNM classification of renal tumors and to perform a critical analysis of the recent evidence in order to identify the limitations of this new staging system. A search of the english literature was performed through the Medline and Pubmed database using the following keywords: renal cell carcinoma, staging system and TNM. Overall, 2600 references were initially scrutinized. Forty papers were selected based on their pertinence with the topic of the review, level of evidence provided and overall contribution to the field. Few changes have been made in the current version of the TNM staging system of renal tumors. pT2 tumors have been divided in 2 subgroups based on tumor size with a cut-off at 10 cm; the invasion of the renal vein was classified as pT3a; finally, the invasion of the ispsilateral adrenal gland was classified as pT4. However, other changes were suggested by the analysis of the recent literature and have not been introduced in this new version. Further improvements of the TNM classification for renal tumors are needed especially with regard to locally advanced tumors and node-positive disease, in order to improve the accuracy of this important prognostic tool in renal oncology.