Primary renal neuroendocrine neoplasms: A systematic literature review, report of four local cases, and original survival analysis of 63 patients from a national registry 2012-2018

Primary renal neuroendocrine neoplasms (NEN) are rare. We aimed to conduct a systematic review, present local cases, and analyse data from the England's National Cancer Registration and Analysis Service (NCRAS) to provide comprehensive evidence on clinical experience, incidence, and survival to better characterize these tumours. First, a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method; second, a synthesis of local cases; and, finally, a retrospective population-based cohort analysis of renal NEN recorded between 2012 and 2018 on NCRAS were performed. Kaplan-Meier estimator was used to calculate overall survival and Cox proportional hazard regression to identify prognostic factors. Systematic review identified 48 articles and the evidence was summarized and presented. We reported data from four local cases presenting with abdominal and back pain but without carcinoid syndrome. In population-based analysis, we identified 63 cases of renal NEN between 2012 and 2018 from the registry. Age-standardized incidence was 0.09-0.32 per million with a median age of 64 years (interquartile range = 48-72 years). Survival was worse in males and those aged 64 years and over. Five-year survival for renal neuroendocrine tumours (NET) was 69.8% (95% confidence interval = 66.6-72.7) and neuroendocrine carcinomas (NEC) was 38.4% (95% confidence interval = 34.6-42.0). No independent predictive factor was identified in the multivariable analyses. We have given a systematic review of evidence, published local experience, and reported incidence and survival of renal NEN in England for the first time. We have provided clinicians with evidence on diagnosis and proposed a treatment algorithm of theses rare tumours. The incidence and median age of presentation in England is similar to other published series. Renal NET has better survival than renal NEC as expected. A uniform classification system would reduce inconsistencies in reporting and standardize treatment decisions for this neoplasia.