Can pre- and postoperative magnetic resonance imaging predict recurrence-free survival after whole-gland high-intensity focused ablation for prostate cancer?

OBJECTIVES: Our aim was to assess whether magnetic resonance imaging (MRI) features predict recurrence-free survival (RFS) after prostate cancer high-intensity focused ultrasound (HIFU) ablation. METHODS: We retrospectively selected 81 patients who underwent (i) whole-gland HIFU ablation between 2007 and 2011 as first-line therapy or salvage treatment after radiotherapy or brachytherapy, and (ii) pre- and postoperative MRI. On preoperative imaging, two senior (R1, R2) and one junior (R3) readers assessed the number of sectors invaded by the lesion with the highest Likert score (dominant lesion) using a 27-sector diagram. On postoperative imaging, readers assessed destruction of the dominant lesion using a three-level score. Multivariate analysis included the number of sectors invaded by the dominant lesion, its Likert and destruction scores, the pre-HIFU prostate-specific antigen (PSA) level, Gleason score, and the clinical setting (primary/salvage). RESULTS: The most significant predictor was the number of prostate sectors invaded by the dominant lesion for R2 and R3 (p≤0.001) and the destruction score of the dominant lesion for R1 (p = 0.011). The pre-HIFU PSA level was an independent predictor for R2 (p = 0.014), but with only marginal significance for R1 (p = 0.059) and R3 (p = 0.053). CONCLUSION: The dominant lesion's size and destruction assessed by MRI provide independent prognostic information compared with usual predictors. KEY POINTS: • The size of the MR-dominant lesion significantly influences post-HIFU recurrence-free survival. • The destruction score of the MR-dominant lesion predicts post-HIFU recurrence-free survival. • Patients with a completely devascularized MR-dominant lesion show better recurrence-free survival • Pre- and post-HIFU MRI provide prognostic information independent of usual predictors.