Utility of fusion biopsy for choosing prostate cancer patients eligible for focal therapy

Abstract

Background. Focal therapies for prostate cancer (PCa) can preserve the quality of life; however, their application is limited by lack of confidence in identifying the exact tumor location.Aim. To evaluate the utility of fusion biopsy for choosing PCa patients eligible for focal therapy with subsequent confirmation by the analysis of radical prostatectomy (RPE) samples.Materials and methods. This study included 122 patients with histologically verified stage Т1–2N0M0 PCa treated in N.A. Lopatkin Research Institute of Urology and Interventional Radiology, a branch of the National Medical Research Radiology Center. Their mean age was 65.2 ± 6.8 years. All patients underwent multiparametric magnetic resonance imaging and fusion biopsy (samples were collected from targeted areas in combination with a standard biopsy), followed by histological examination of biopsy samples and mapping of the affected areas. Twenty-eight patient underwent RPE.Results. Study participants were distributed as follows by their Prostate Imaging Reporting and Data System (PI-RADS) score: 5 points in 23 patients (18.9 %), 4 points in 57 patients (46.7 %), and 3 points in 42 patients (34.4 %). Targeted biopsy revealed cancer in 105 out of 122 patients (86.1 %) in at least one sample. Seventeen targeted biopsy samples were negative. The majority of patients had ISUP (International Society of Urological Pathology) grade 1 (n = 57; 46.8 %) and grade 2 (n = 33; 27.0 %) tumors. Comparison of biopsy findings and results of pathological examination of the removed prostate demonstrated significant discrepancies in the distribution of cases by their ISUP grades. Almost half of the patients (46.8 %) were diagnosed with ISUP grade 1 tumors after biopsy, while the assessment of RPE specimen demonstrated ISUP grade 1 tumors only in 21.4 % of patients. ISUP grade 3 tumors were diagnosed in 16.4 % and 35.7 % of patients using biopsy- and RPE-derived specimens, respectively. The proportions of ISUP grade 2, 4, and 5 tumors were similar with both methods. In 27 out of 28 cases, examination of biopsy- and RPE-derived specimens demonstrated complete agreement in terms of tumor location. Importantly, this study included only patients with histologically confirmed PCa; so we didn’t evaluate the effectiveness of biopsy for cancer diagnosis. Focal therapy could have been considered in 22 out of 28 patients (78.6 %) who underwent RPE. This proportion of focal therapy-eligible patients is almost equal to that identified by fusion biopsy (75.4 %).Conclusion. Multiparametric magnetic resonance imaging in combination with targeted and multifocal prostate biopsy allow precise identification of candidates eligible for focal therapy with a relatively low risk of an erroneous conclusion.