## 2 Importance of miRNAs in Urinary Tract Carcinoma  
### Renal Carcinoma  
Renal carcinoma is a renal parenchymal tumor with the symptoms of hematuria, lateral abdominal pain, abdominal mass, and fever [26]. It is often detected by imaging studies, such as abdominal ultrasonography, CT, and MRI during medical checkups and other detailed examinations. In advanced stages, tumor-associated syndrome occurs in 20% of patients. Increased erythropoietin activity may also cause hyperplasia. Epidemiologically, renal cell carcinoma affects approximately 6 in 100,000 people--or approximately 1% of all cancers--and is slightly more common in males [27] (Cancer Today; [[https://gco.iarc.fr/today/fact-sheets-cancers](https://gco.iarc.fr/today/fact-sheets-cancers)]([https://gco.iarc.fr/today/fact-sheets-cancers](https://gco.iarc.fr/today/fact-sheets-cancers)), accessed on 19 June 2022). The incidence rate of renal carcinoma increases around the age of 50 years; as the patient ages, the incident rate increases until they reach 70 years old. The risk factors for renal carcinoma include acquired factors such as smoking, obesity, excessive use of phenacetin, acquired cystic kidney disease, and dialysis kidney disease; various chemical stimuli such as contrast media, asbestos, cadmium, and leather tannins; exposure to petroleum products; and familial syndromes such as von Hippel-Lindau (VHL) disease, which results from genetic abnormalities (Figure 2) [21; 26; 28; 29; 30]. The 5-year relative survival rate for renal carcinoma is 68.6% (70.4% in men and 64.8% in women), while tumors confined to the kidney have a high survival rate of 94.3% [27; 31]. Therefore, the prognosis for renal cancer is very favorable if the disease is detected early, even if it is detected incidentally. However, because renal cell carcinoma is a highly vascularized tumor, distant metastasis is also frequent, and there are rare cases in which the carcinoma recurs due to distant metastasis after a long survival period. Once a patient is diagnosed with renal cancer, a highly sensitive and accurate means of diagnosis is needed, even after initial treatment, through screening and recurrence monitoring tests [32; 33; 34]. Currently, there is a lack of effective tumor markers in both the blood and urine. In advanced and metastatic renal carcinoma, the presence or absence of anemia, increased calcium levels, LDH, and CRP can predict prognosis to some extent; however, there is no marker for detecting localized tumors or signs of recurrence. Our understanding of miRNA function in renal carcinoma has increased greatly over the past decade, and many reports have been published [35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48]. Most of these studies are beginning to reveal the functions of miRNAs targeting molecules related to proliferation signaling and angiogenesis [37; 38; 39; 40; 45; 47; 49]. Nevertheless, we are yet to establish tumor markers specific to renal cancer. This is because the functional analysis of miRNAs associated with vascular endothelial growth factor (VEGF)/VEGF receptor (VEGF)-related proliferation signals and VHL gene expression has particularly attracted the attention of the scientific community in the reports to date [37; 38; 39; 40; 45; 46; 47; 47]. Molecular targeted therapies have been commercialized for VEGF/VEGF signaling, and various kinase inhibitors and immune checkpoint inhibitors have been used as molecular targeted therapies to improve prognoses [36; 41; 42; 43; 50; 51]. An increase in proliferation signals is assumed to be a common mechanism in various carcinomas. Although it provides a wide range of therapeutic options, it lacks specificity as a diagnostic or prognostic factor. In order to identify molecules with high specificity for renal cell carcinoma, miRNAs that have important roles in renal cell carcinoma should be identified along with the putative target molecules. After elucidating their functions, these new diagnostic markers specific to renal cell carcinoma can be expected to be put into practical use.