Renal cell carcinoma (RCC) is relatively common pathology that is found roughly in 3 % of all cases of malignant neoplasia in adults and approximately in 90 % of malignant tumors arising because of a kidney. Associations between imaging features and genomic landscape of RCC have been recently investigated in order to characterize better tumor diagnosting more precisely, staging and establishing more accurate prognosis comparing to classic histopathologic approach. Such integration of imaging and molecular biomarkers has led to novel concept of “radiogenomics”. In our previous work we have already described usefulness of expression of mi-R-15a measured in urine during RCC diagnostics. Moreover, high miR-15a expression values have been significantly associated with poor survival rates in patients with RCC.
The purpose. The goal of the study is investigation of the associations between cross-sectional imaging features of RCC and urine expression levels of miR-15a.
Materials and methods. 52 adult patients with RCC according to clinical and imaging data have been engaged into study. In all patients’ multiphase CT or MRI imaging with contrast enhancement has been performed prior to surgical treatment using standard abdominal protocols.
Urine collecting and miR-15a expression measuring has been performed using quantitative polymerase chain reaction. Associations between miR-15a expression and such RCC imaging features as necrosis, renal vein invasion, presence of intratumoral calcifications, definition of tumor margin and architecture, presence of collecting system invasion, intratumoral hypervascularity, homogeneous or nodular tumor enhancement pattern on nephrographic phase images have been assessed. All patients have been treated surgically with the following pathologic analysis.
Results. RCC cases have been classified concordantly to AJCC cancer staging manual: T1aN0M0 (n = 13, 25,0 %), T1bN0M0 (n = 15, 28,85 %), T2aN0M0 (n = 12, 23,08 %), T2bN0M0 (n = 5, 9,62 %), T3aN0M0 (n = 4, 7,69 %), T3aN1M0 (n = 3, 5,77 %). RCCs have been classified according to histologic subtypes – clear cell RCC (n = 22), papillary RCC (n = 16), chromophobe RCC (n = 14). Simplified two-tiered Fuhrman grading system has been used, in which grades I and II (low grade, n = 12) and grades III and IV (high grade, n = 10) have been combined.
The expression values of miR-15a in urine of patients with RCC have varied from 91,35 to 5,52 relative fluorescence units (RFU), mean – 54,58 ± 37,76 RFU. High expression levels of miR- 15a (> 25 RFU) in patients with RCC have been associated with necrosis (p < 0,05), ill-defined margins of the lesion (p < 0,05) and intratumoral hypervascularity (p < 0,01). Lower miR-15a expression levels (< 25 RFU) have been associated with imaging evidence of renal vein (p < 0,05) and collecting system (p < 0,05) invasion, nodular tumor enhancement pattern (p < 0,05) and multicystic tumor architecture (p < 0,05). There has been no significant association between miR- 15a expression and presence of intratumoral calcifications on cross-sectional images (p>0,05). Conclusions. Radiogenomic analysis may provide valuable information for predicting of emiR-15a expression levels in urine of patients with RCC. In clinical conditions under which there is no possibility to perform genetic assay, imaging features of RCC can be used as surrogates of miR-15a expression to perform prognostication of disease biologic behavior.
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