Standardization of definitions in focal therapy of prostate cancer: report from a Delphi consensus project

Purpose: To reach standardized terminology in focal therapy (FT) for prostate cancer (PCa). Methods: A four-stage modified Delphi consensus project was undertaken among a panel of international experts in the field of FT for PCa. Data on terminology in FT was collected from the panel by three rounds of online questionnaires. During a face-to-face meeting on June 21, 2015, attended by 38 experts, all data from the online rounds were reviewed and recommendations for definitions were formulated. Results: Consensus was attained on 23 of 27 topics; Targeted FT was defined as a lesion-based treatment strategy, treating all identified significant cancer foci; FT was generically defined as an anatomy-based (zonal) treatment strategy. Treatment failure due to the ablative energy inadequately destroying treated tissue is defined as ablation failure. In targeting failure the energy is not adequately applied to the tumor spatially and selection failure occurs when a patient was wrongfully selected for FT. No definition of biochemical recurrence can be recommended based on the current data. Important definitions for outcome measures are potency (minimum IIEF-5 score of 21), incontinence (new need for pads or leakage) and deterioration in urinary function (increase in IPSS >5 points). No agreement on the best quality of life tool was established, but UCLA-EPIC and EORTC-QLQ-30 were most commonly supported by the experts. A complete overview of statements is presented in the text. Conclusion: Focal therapy is an emerging field of PCa therapeutics. Standardization of definitions helps to create comparable research results and facilitate clear communication in clinical practice.