Non-Invasive Diagnostics of Small Renal Masses

Overview

NiSAR is a Ph.D. study and consists of three substudies. Renal cancer is one of the most deadly urologic malignancies and accounts for 900 new cases and 300 deaths per year. An increase in the use of imaging diagnostics has yielded a rise in the incidental detection of small renal masses (SRM), meaning tumors \<4cm (T1a). Kidney biopsies are the gold standard for diagnosing SRM but has an inherent risk of infections, retroperitoneal bleeding and in rare cases loss of kidney function. This is problematic since up to 30% of SRM are benign. This Ph.D. consists of three studies that all aim to develop new minimally invasive modalities for diagnosing SRM. Patients eligible for these studies are diagnosed with SRM at one of the departments of Urology in the southern region of Denmark. Studies 1 and 2 aims to find circulating biomarkers, in the form of DNA and messenger ribonucleic acid (mRNA) contained in micro vesicles secreted into blood by renal cell cancers and find changes in biomarkers levels after surgery. Study 3 aim to determine the potential of multiplanar MRI (mpMRI) to discriminate between benign and malign SRM. Potentially this can lead to a fundamental change of the way urologists diagnose and monitor SRM and renal cell cancer in general. The investigators will also build a research biobank for future research.

Study 1: Trial objective: Identification of biomarkers in blood and urine and to set the basis for a minimally invasive diagnostic program for SRM. Method: Sample collection: All blood samples will be collected in ethylendiamin-tetraacetate (EDTA) containing tubes. two samples are then centrifugated at 2000 G for 10 minutes to isolate plasma, which then are stored at -80oC. The remaining 2 samples are stored at -80oC as is. Total nucleic acid (TNA) will be extracted from concentrated urine and plasma samples as previously described using a NucliSENS easy MAG instrument. Extracted TNA will then be used for targeted immune- and oncologic profiling (mutations and expression) using next generation sequencing (NGS)-based RNA and DNA sequencing. The additional core sample from kidney tumor will be stored without preservatives for NGS-based DNA and RNA-seq analysis. Study 2: Trial objective: Identification of changes in circulating biomarkers after curative treatment in patients with biopsy verified renal cancer. Methods: Patient recruitment: Patients will be enrolled in study 2 in the same manner as study 1. Sample collection: In addition to the first four samples four additional blood samples (20 ml) will be taken 1 month and 6 months after curative treatment from each patient. All samples will be coded and given an ID according to patient´s CPR number using the RedCap informatic coding system. Sample storage, preparation and analysis: Blood and urine samples will be handled in the same manner as in study 1. Statistical Analysis for study 1 and 2: Exploratory analysis of the data will be performed on molecular expression levels of specific sequences identified, an unsupervised hierarchical clustering will be fit and heat maps will be produced. Properties of clustered elements will be further matched with histopathological results to search for histological aggregation patterns. Expression levels of the sequences identified, in blood and urine will be compared by means of Whitney U test and Kruskal-Wallis test. Changes in levels of expression from pre-operative to post-operative will be evaluated with Friedman´s ANOVA and subsequent post-hoc pairwise comparison with Wilcoxon's signed rank test with Bonferroni correction. Receiver operating characteristic curve analysis will be further performed on pre-operative samples, to test for validity of the assays for each marker to discriminate between benignant histology and malignancy, with a cut-off for area under curve (AUC) of 0.75. Sample size The minimal sample size required for achieving a statistical power of 80% with a significance level of 0.05 and an expected dropout rate of 15% will be 155 patients. Calculations for sample size have been computed with the GPower software (Düsseldorf, DE). Study 3: Trial objective: To investigate the diagnostic value of mpMRI in determining malignancy in SRM. Method: Patient recruitment: After providing a written consent a mpMRI will be scheduled at the same day but prior to the primary biopsy. All mpMRIs will be performed locally and the pictures transferred to Odense University Hospital where a specialist radiologist, will examine the scans in a blinded fashion, meaning that he will be ignorant to the pathologist´s diagnosis. The result will be stored in a coded RedCAP database. MpMRIs are performed according to a standard protocol and include the following sequences: T1 (with reduced affinity for fatty tissue) +/- contrast, diffusion weighted sequences and wash in/wash out.