Predictive ability of prebiopsy magnetic resonance imaging and biopsy for side-specific negative lymph node metastasis at radical prostatectomy

Background Prostate cancer localization is reportedly associated with the laterality of lymph node metastasis. Thus, it may be feasible to predict side-specific lymph node metastasis (LNM) at radical prostatectomy (RP). To investigate whether multiparametric magnetic resonance imaging and biopsy findings can predict side-specific negative LNM and to explore the feasibility of unilateral lymph node dissection (LND) at RP. Methods A total of 500 patients who were diagnosed with prostate cancer with prebiopsy multiparametric magnetic resonance imaging of the prostate and subsequent prostate biopsy and who underwent RP and extended LND without neoadjuvant treatment were enrolled. Multiparametric magnetic resonance imaging, biopsy findings, and LNM were assessed for each side. The negative predictive value (NPV) of multiparametric magnetic resonance imaging or biopsy or both for ipsilateral LNM was examined. Results LNM was found in 9.2% (46/500) and 15.6% (28/180) of patients in the overall and high-risk cohorts, respectively. Magnetic resonance imaging and biopsy findings were negative in 408 and 262 sides, respectively, in the overall cohort and 144 and 100 sides, respectively, in the high-risk cohort. The NPVs of magnetic resonance imaging, biopsy, and both for ipsilateral LNM were 98.3%, 98.5%, and 99.1%, respectively, in the overall cohort, and 95.8%, 97.1%, and 97.6%, respectively, in the high-risk cohort. Conclusions Unilateral LND may be indicated based on side-specific LNM risk as assessed by prebiopsy multiparametric magnetic resonance imaging and biopsy.