Detection of HPV infection in urothelial carcinoma using RNAscope: Clinicopathological characterization.

BACKGROUND: Human papillomavirus (HPV) is a well-established mucosotropic carcinogen, but its impact on urothelial neoplasm is unclear. We aimed to clarify the clinical and pathological features of HPV-related urothelial carcinoma (UC). METHODS: Tissue samples of 228 cases of UC were obtained from the bladder, upper and lower urinary tract, and metastatic sites to construct a tissue microarray. The samples were analyzed for the presence of HPV by a highly sensitive and specific mRNA in situ hybridization (RISH) technique (RNAscope) with a probe that can detect 18 varieties of high-risk HPV. We also conducted immunohistochemistry (IHC) for a major HPV capsid antibody and DNA-PCR. RESULTS: The HPV detection rates varied among the methods; probably due to low HPV copy numbers in UC tissues and the insufficient specificity and sensitivity of the IHC and PCR assays. The RISH method had the highest accuracy and identified HPV infection in 12 (5.2%) of the cases. The histopathological analysis of the HPV-positive UC showed six cases of usual type UC, five cases of UC with squamous differentiation (UC_SqD), and one case of micropapillary UC. The HPV detection rate was six-fold higher in the cases of UC_SqD than in the other variants of UC (odds ratio [OR] =8.9, p = 0.002). In addition, HPV infection showed a significant association with tumor grade (OR =9.8, p = 0.03) and stage (OR =4.7, p = 0.03) of UC. Moreover, the metastatic rate was higher in HPV-positive than in negative UC (OR =3.4). CONCLUSION: These data indicate that although the incidence of HPV infection in UC is low, it is significantly associated with squamous differentiation and poor prognosis. Furthermore, our observations show that RNAscope is an ideal method for HPV detection in UC compared with the other standard approaches such as IHC and PCR assays.

Resolution of a High Grade and Metastatic BK Polyomavirus-Associated Urothelial Cell Carcinoma Following Radical Allograft Nephroureterectomy and Immune Checkpoint Treatment: A Case Report.

BACKGROUND: BK viral infection in the posttransplant setting continues to cause serious morbidity with effects ranging from allograft nephropathy and dysfunction to urothelial malignancy. RESULTS: In this report, we present a patient that developed BK-associated nephropathy and, 6 years later, locally advanced urothelial malignancy in the renal allograft with nodal, muscle, and extremity involvement. Following radical allograft nephroureterectomy, he was treated with palliative radiation and the immune checkpoint inhibitor atezolizumab. Follow-up imaging at 1 year demonstrated radiographic complete response. CONCLUSIONS: This report supports the growing body of evidence supporting the association of urothelial malignancy and BK virus infection in renal transplant recipients. Further, it highlights the novel application of immune checkpoint inhibitors in the treatment of advanced posttransplant malignancy, in particular when the allograft is removed and the tumor is possibly of donor origin.

Cytomorphologic findings of cervical Pap smears from female-to-male transgender patients on testosterone therapy.

BACKGROUND: The cervical cancer screening recommendation for transgender female-to-male (FTM) patients is the same as that for cisgender females. A lack of literature on testosterone-induced changes in cervical cytology in these patients may result in interpretation errors, especially without a proper clinical history. The aim of this study was to delineate the Papanicolaou (Pap) test findings in this patient population. METHODS: A pathology laboratory information system was used to obtain a cohort of FTM transgender patients on testosterone therapy (2009-2019). A cohort of age-matched, atrophic, control cisgender female patients (postpartum or menopausal) was selected. A retrospective review of the cytomorphologic findings on cervical Pap smears, pertinent follow-up, and human papillomavirus (HPV) test results was performed. RESULTS: Fourteen transgender patients (age range, 21-64 years; mean age, 42.5 years) receiving testosterone therapy with 17 Pap smears were identified. One of the 5 available HPV tests was positive for HPV, and 4 were negative. A Pap smear review revealed the following: negative for intraepithelial lesion (NILM; 82.4%), unsatisfactory (5.9%), atypical squamous cells of undetermined significance (ASCUS; 5.9%), and low-grade squamous intraepithelial lesion (5.9%). The Pap smears of the atrophic cisgender cohort (102 patients) revealed the following: NILM (92.5%), unsatisfactory (0.9%), ASCUS (5.6%), and high-grade squamous intraepithelial lesion (0.9%). The difference between the rates of epithelial cell abnormality in the 2 cohorts was not statistically significant. Although atrophy was noted in both groups, cytomorphologic findings of transitional cell metaplasia (TCM; 88.2%) and "small cells" (82.4%) were characteristic of the testosterone-treated transgender cohort. Histologic correlates of TCM and small cells were noted in hysterectomy specimens from 6 patients. CONCLUSIONS: Small cells and TCM are common cytomorphologic findings in Pap smears of testosterone-treated transgender (FTM) patients. On the basis of histologic follow-up, small cells most likely represent atrophic parabasal cells of cervical-vaginal epithelium.

Variant morphology and random chromosomal integration of BK polyomavirus in posttransplant urothelial carcinomas.

BK polyomavirus (BKPyV) causes major complications in solid organ transplant recipients but little is known about its role in the development of urothelial carcinoma (UC) during immunosuppression. Immunohistochemistry (IHC) screening for polyomavirus large T antigen (LTag) was performed in 94 micropapillary UC (MPUC), 480 unselected UC, 199 muscle invasive UC (including 83 UC with variant differentiation), 76 cases of plasmocytoid, nested and large nested UC and 15 posttransplant UC. LTag expressing UC were reevaluated regarding their histomorphological features and characterized by IHC for p53 and HER2, chromogenic in situ hybridization for HER2 and SNaPshot analysis of the TERT promoter and HRAS. Real-time PCR and next generation sequencing (NGS) were performed to search for BKPyV-DNA and for variants in the tumor and viral genomes. We detected five LTag expressing UC which were diagnosed between 2 and 18 years after kidney (n = 4) or heart (n = 1) transplantation. 89 MPUC without history of organ transplantation and overall 755 UC (including cases with variant histology) were LTag negative. Of the five LTag expressing UC, three were MPUC, one showed extensive divergent differentiation with Mullerian type clear cell carcinoma, and one displayed focal villoglandular differentiation. All five tumors had aberrant nuclear p53 expression, 2/5 were HER2-amplified, and 3/5 had TERT promoter mutations. Within the 50 most common cancer related genes altered in UC we detected very few alterations and no TP53 mutations. BKPyV-DNA was present in 5/5 UC, chromosomal integration of the BKPyV genome was detectable in 4/5 UC. Two UC with BKPyV integration showed small deletions in the BKPyV noncoding control region (NCCR). The only UC without detectable BKPyV integration had a high viral load of human herpesvirus 6 (HHV-6). Our results suggest that LTag expression of integrated BKPyV genomes and resulting p53 inactivation lead to aggressive high-grade UC with unusual, often micropapillary morphology.

RNA Expression Profiling of Lymphoepithelioma-Like Carcinoma of the Bladder Reveals a Basal-Like Molecular Subtype.

Lymphoepithelioma-like carcinoma of the bladder (LELC-B) is a rare subtype of urothelial carcinoma consisting of undifferentiated epithelial cells within a dense inflammatory cell infiltrate. We set out to molecularly characterize LELC-B through RNA expression profiling as well as immunohistochemistry (IHC) to understand its underlying biology. Sixteen cases of LELC-B were identified at Johns Hopkins University. RNA sequencing was performed on 14 cases. IHC staining for programmed cell death ligand 1 (PD-L1) and mismatch repair proteins MutL homolog 1 (MLH1), MutS homolog 2 (MSH2), MSH6, and PMS1 homolog, mismatch repair system component 2 (PMS2) was performed. Transcriptomic profiling of LELC-B showed that they are enriched in a basal-like phenotype, with 12 of 14 LELC-B cases correlating to the basal centroid of the bladder cancer analysis of subtypes by gene expression 47 (BASE47) predictive analysis of microarrays (PAM) classifier. Gene signature analysis confirmed the lymphocyte infiltration profile consistent with the histomorphology. LELC-B lacked features to explain the robust lymphocytic infiltrate, such as loss of mismatch repair protein expression or expression of Epstein-Barr virus transcripts. Nonetheless, PD-L1 IHC was positive in 93% of LELC cases. Our study demonstrates that LELC-B tumors are enriched in a basal-like molecular subtype and share a high level of immune infiltration and PD-L1 expression, similar to basal tumors. The basal-like phenotype is consistent with the known sensitivity of LELC-B to chemotherapy and suggests that immune checkpoint therapy should be explored in this rare disease.

HPV related cloacogenic carcinoma of the anal canal with divergent histomorphology.

Cloacogenic carcinoma also known as basaloid squamous cell carcinoma is a rare anorectal tumor presenting with varied histomorphology. In this case report, we describe a case of 58-year-old man presenting with bleeding per rectum and pain. A polypoidal tumor was noted in anal canal which on microscopy was diagnosed to be cloacogenic carcinoma with transitional carcinoma-like, basaloid and mucinous patterns. An unusual finding in the present case was the presence of signet ring cells in the mucinous areas. A thorough knowledge of the wide histomorphological spectrum of the tumor and a limited IHC panel are crucial for the diagnosis. Here, we also present a review of literature and describe in detail the origin and histopathological features of the tumor.

Association Between Human Papillomavirus and Transitional Cell Carcinoma of the Bladder.

PURPOSE: Bladder carcinoma is one of the most common malignancies in worldwide. Among several risk factors, Human Papilloma Virus (HPV) have been presumed to play a causative role in the etiology of bladder cell carcinoma. The aim of this study was to evaluate the involvement of HPV infection in biopsy specimens of patients with transitional cell carcinoma at the west of Iran. MATERIALS AND METHODS: In this study, 97 biopsy specimens including 67 patients with transitional cell carcinoma (TCC) of bladder and 30 cases of control group with the mean age of 63 years were studied using immunohistochemistry to identify HPV. RESULTS: 22.4% of patients with TCC of bladder and 3.3% of control group were positive for HPV with a meaningful relation (P=.019). The prevalence of HPV was 4.3 fold higher in men than women. Most TCC patients werebelonged to grades II and III. CONCLUSION: Considering the higher incidence of HPV positivity in patients with TCC of bladder compared to control group, it seems to be a meaningful association between HPV infection and TCC of bladder, at least in the west of Iran.

Human Polyomavirus Is Associated With Earlier Onset of Upper Urinary Tract Urothelial Carcinoma in Patients After Kidney Transplantation.

OBJECTIVES: Polyomavirus has been reported to be oncogenic due to viral integration into the human genome. A relatively high prevalence of upper urinary tract urothelial carcinoma (UTUC) was noted after kidney transplantation (KT) in Taiwan. However, little was known about the impact of polyomavirus on the urothelial cancer behavior. Therefore, the aim of this study is to analyze the characteristics of polyomavirus-related UTUC after KT. METHODS: From 2005 to 2014, 27 patients were found to have UTUCs after KT. All the patients underwent standard nephroureterectomy. Detailed perioperative parameters were obtained from chart records. A qualified pathologist who is blinded to the clinical outcome examined large T antigen expression and pathological features. All the patients were divided into two groups according to positive or negative expression of large T antigen. RESULTS: In the patient demography, a significantly younger median age was found in patients with large T antigen-positive UTUCs compared with the negative control group (48.1 ± 8.3 years versus 54.6 ± 4.1 years, respectively, P = .013). As for the pathological features and oncologic outcome, there were no obvious differences between these two groups. Non-organ-confined status and positive lymphovascular invasion are prognostic factors associated with systemic disease recurrence (P = .017 and .001, respectively). CONCLUSIONS: Although UTUC commonly develops in the elderly, earlier onset of post-KT UTUCs was observed especially in patients with positive large T antigen expression in our cohort. This preliminary result provides valuable experience suggesting more frequent upper urinary tract screening for polyomavirus infected patients after KT in Taiwan.

Lentivirus-mediated p21/Waf-1 short hairpin RNA enhances the cytotoxic effects and replicative potential of a bladder cancer-specific oncolytic adenovirus in vitro.

Our previous work confirmed that the bladder cancer-specific oncolytic adenovirus Ad/PSCAE/UPII/E1A could selectively replicate in bladder cancer cells, thus causing specific tumor cell lysis. The replicative potential is a crucial factor in determining the therapeutic efficacy of oncolytic adenoviruses. However, viral replication is attenuated by the low-activity promoter that we used, thus compromising viral cytotoxicity. In this study, we investigated the effect of the cell cycle-dependent kinase inhibitor p21/Waf-1 on an adenovirus. We used lentivirus-mediated short hairpin RNA to knock down p21/Waf-1 in two bladder cancer cell lines EJ and 5637. The p21/Waf-1 knockdown not only induced stronger cytopathic effects but also augmented apoptosis, which was closely associated with the enhancement of Fas and the subsequent significant activation of caspase-3. A replicative assay showed that p21/Waf-1 knockdown increased the viral particle production. Western blot analysis confirmed that p21/Waf-1 knockdown upregulated the expression of androgen receptor (AR) and two adenovirus replication indicators E1A and hexon. A luciferase activity assay indicated higher transcriptional activity of the uroplakin II (UPII) promoter in the p21/Waf-1 knockdown cells, and one possible mechanism could be that the increased expression of AR induced the UPII promoter through the AR-binding sites of the prostate stem cell antigen enhancer. These findings indicating that p21/Waf-1 knockdown could enhance cell killing and viral replication have significant implications for the development of bladder cancer-specific oncolytic adenovirus therapies.

Loss of Cell Differentiation in HPV-Associated Bladder Cancer.

Medical histories of 101 urothelial bladder cancer patients were compared with the results of morphological analysis and biomolecular detection of human papilloma viruses (HPV) in the tumor specimens. DNA of HPV16 (the major type of virus responsible for appearance of cervical carcinoma) was detected in 38 specimens, while mRNA of E6 and E7 oncogenes and E7 oncoprotein of HPV16 were observed in 13 specimens. HPV-positive bladder cancer was characterized by higher degree of cell anaplasia than HPV-negative cancer; in the primary bladder tumor, HPV was detected more often than in recurrent bladder cancer. These data attest to involvement of HPV16 in the genesis of bladder cancer. No correlations of HPV status of bladder tumor with patient's sex, age, and invasion into the muscle layer were revealed.

[YB-1-based virotherapy: A new therapeutic intervention for transitional cell carcinoma of the bladder?]. / YB-1-basierte Virotherapie : Ein neues Therapiekonzept beim Urothelkarzinom der Harnblase.

Therapeutic intervention using oncolytic viruses is called virotherapy. This type of virus is defined by the ability to replicate in tumor cells only and to destroy these cells upon replication. In addition, this virus type is able to induce a tumor-directed immune response. Early clinical trials have confirmed the safety profile of oncolytic viruses. Currently, different groups are working on the development of oncolytic viruses with a focus on treatment of nonmuscle invasive bladder cancer (NMIBC). A preliminary active recruiting clinical phase II/III trial ongoing in patients with a NMIBC was recently implemented in the United States. Our research group developed an oncolytic adenovirus that will soon enter a clinical phase I trial in patients diagnosed with glioma. This virus is being further modified for the treatment of NMIBC. In this review article, recent developments in the design and use of virotherapy in bladder cancer are summarized.

Human papillomavirus (HPV)-induced neoplasia in the urinary bladder: a missing link?

The discovery that the role human papillomavirus (HPV) plays in the induction of human cancer represents an important achievement in oncologic research. It has taken on even greater importance since the development of vaccines, which promise the hope of preventing these cancers from ever occurring. Because of these important implications, many have attempted to determine a possible role for the virus in cancers of the urinary bladder-an organ in close anatomic proximity to the primary sites of HPV-induced neoplasia and one which already has an established oncogenic infectious agent in Schistosoma haematobium. Here we review the current literature exploring this possible role in the most common subtype of cancer of the urinary bladder, urothelial carcinoma, and two much more rare histologic subtypes that have well established roles for HPV-induced neoplasia in other anatomic sites-squamous cell carcinoma and adenocarcinoma.

Polyomavirus large T antigen is prevalent in urothelial carcinoma post-kidney transplant.

Viral pathogens have been associated with both infectious disease and neoplasia in transplant recipients. Polyomavirus is emerging as a potential causative agent for genitourinary tract cancer in post-kidney transplant patients. Human papillomavirus (HPV) has a proven role in squamous cancers, but has not been studied in genitourinary malignancies in transplantation. Of 2345 kidney transplants performed at our center over the past 20 years, we identified 16 patients with 20 genitourinary cancers (0.7%), including 13 bladder/ureter carcinomas, 5 renal cell carcinomas (RCCs), and 2 prostate carcinomas. We performed immunohistochemical staining for polyomavirus large T antigen and p16, followed by in situ hybridization for HPV in p16+ cases. Four cases of high-grade invasive urothelial bladder carcinomas were positive for large T. Large T+ urothelial carcinomas developed at least 8 years posttransplant in young men, 3 with history of BK polyoma viremia, 2 of whom had native kidney failure due to reflux/obstruction. In situ hybridization for high-risk HPV was negative in all tested cases. Overall, 3 patients died of carcinoma. All 5 RCCs were negative for both large T and p16; 2 prostate cancers were p16 negative and p16+/HPV negative, respectively. Thus, our study shows a relatively high prevalence of large T antigen in urothelial carcinoma in kidney transplant patients (31%), but not in RCC. Although sample size is small, young patients with obstructive disease may be at particular risk for developing large T-positive urothelial carcinoma. Overall, our data further support the necessities of long-term cancer surveillance for renal transplant patients.

Polyoma (BK) virus associated urothelial carcinoma originating within a renal allograft five years following resolution of polyoma virus nephropathy.

A direct role for BK polyomavirus infection in malignant tumors of renal allografts and urinary tract is emerging. Case reports suggest a link between BK virus (BKV) reactivation and development of malignancy in renal allograft recipients. Herein we describe the first case of BKV positive invasive urothelial carcinoma within the renal allograft, presenting with chronic diarrhea and weight loss 5 years following resolution of BK viremia/nephropathy (BKVN). Unique to our case was the remote history of BK viremia/BKVN, rising titer of anti-HLA antibody and presence of renal limited urothelial carcinoma with microinvasion of malignant cells staining positive for SV40 large T antigen (T-Ag). These findings suggest that persistence of subclinical BKV infection within the renal allograft may play a role in the malignant transformation of epithelial cells. Patients with history of BKVN may be at risk for kidney and urinary tract malignancy despite resolution of BK viremia/BKVN.

Genotyping of high-risk human papillomaviruses in p16/Ki-67-positive urothelial carcinoma cells: even a worm will turn.

OBJECTIVE: Co-expression of p16INK4a protein and Ki-67 (p16/Ki-67) is noted in almost all high-grade urothelial lesions. However, the aetiological role or, conversely, the absence of causative effect of high-risk human papillomaviruses (hr-HPVs) has not been documented. The purpose of this study is to evaluate HPV DNA in p16/Ki-67-positive, high-grade urothelial tumour cells. METHODS: Fifty-seven urine samples collected from 50 patients, including 55 histologically proven high-grade proliferations and two cases with clinical evidence of malignancy, were analysed for p16/Ki-67. Immunolabelling was performed in destained Papanicolaou-stained slides after ThinPrep(®) processing. HPV genotyping was performed by polymerase chain reaction (PCR) using a DNA microarray for 35 HPV types. Confirmation of the presence (or absence) of HPV in tissue samples was verified using a reasoned approach combining PCR and in situ hybridization (ISH) for hr-HPVs. RESULTS: Co-expression of p16/Ki-67 was noted in 43 of 57 (75.4%) cases. In these, hr-HPVs 16, 31 and 70, and low risk HPV 84, were detected in the urine in four patients (8%). Upregulation of p16INK4a protein was confirmed on bladder biopsy or transurethral resection specimens, but PCR and ISH for hr-HPVs were both negative on the tissue sections. CONCLUSION: Our results show a low prevalence of HPV infection in the urinary tract of patients with p16/Ki-67-positive urothelial malignancy. The study confirms that the deregulated cell cycle, as demonstrated by p16/Ki-67 dual labelling, is independent of the oncogenic action of hr-HPVs in high-grade urothelial proliferations.

p16(INK4a) overexpression is not linked to oncogenic human papillomaviruses in patients with high-grade urothelial cancer cells.

BACKGROUND: p16(INK4a) Is overexpressed in almost all precancerous and carcinomatous lesions of the uterine cervix, secondary to interference between high-risk human papillomaviruses (hr-HPVs) and the retinoblastoma gene product. Overexpression of p16(INK4a) has also been identified in patients with high-grade urothelial lesions, both cytologically and histologically. However, the etiological role of HPV has not been documented except in inverted papillomas, low-grade bladder tumors, and younger patients. We therefore attempted to verify if HPV DNA was detectable in p16(INK4a) -positive urothelial tumors. METHODS: A total of 90 urinary cytology samples (33 negative/low-grade cases and 57 high-grade proliferations) were analyzed for p16(INK4a) and HPV DNA. HPV genotyping was performed by polymerase chain reaction using a low-density DNA microarray enabling the detection of 35 HPVs. A reasoned approach combining tissue genotyping and in situ hybridization (ISH) for hr-HPVs was used in patients with urinary HPV. RESULTS: Low-risk HPV (HPV-84) and hr-HPVs (HPV-16, -31, and -70) were detected. The prevalence of hr-HPVs in the urine was low: 5 of 82 patients (6.1%) and only 4 of 50 patients (8.0%) with high-grade urothelial malignancy. p16(INK4a) overexpression was noted in 49 high-grade samples (85.9%). In patients with p16(INK4a) -positive tumor cells and hr-HPV in the urine, HPV genotyping and ISH for hr-HPVs were negative in matched tissue sections. CONCLUSIONS: Our study shows a low prevalence of hr-HPVs in the urine of patients with high-grade urothelial malignancy. In those, p16(INK4a) overexpression occurs in the absence of demonstrable HPV DNA in the tissue sections, contrary to what is noted in gynecopathology.

Mutations in 3'-long terminal repeat of HERV-W family in chromosome 7 upregulate syncytin-1 expression in urothelial cell carcinoma of the bladder through interacting with c-Myb.

Human endogenous retrovirus (HERV) accounts for ∼8% of the human genome. Recent studies have reported that multiple HERV genes and long terminal repeats (LTRs) are involved in human tumorigenesis. Here we demonstrated that HERV-W env (syncytin-1) was overexpressed in 75.6% (62/82) of urothelial cell carcinoma (UCC) tissues of the bladder compared with only 6.1% (5/82) of matched tumor-adjacent tissues (P<0.001). Syncytin-1 overexpression increased proliferation and viability of immortalized human uroepithelial cells. Colony-formation experiments and in-vivo tumor xenografts suggested that syncytin-1 overexpression had oncogenic potential. Syncytin-1 3'-LTR mutations (142T>C and 277A>G) were present in 87.8% (72/82) of UCC tissues. Normal 3'-LTR was found in 12.2% (10/82) of UCC tissues compared with 95.1% (78/82) of matched tumor-adjacent tissues (P<0.001). Interestingly, 3'-LTR mutations were significantly associated with syncytin-1 overexpression. Luciferase assay and expression analysis revealed that 3'-LTR mutations, especially the 142T>C mutation, enhanced the syncytin-1 promoter activity and expression. In-silico analysis, electrophoretic mobility shift assays and chromatin immunoprecipitation assays demonstrated the binding of c-Myb to 3'-LTRs when the mutations occurred. This alternative interaction was found to be dependent on 142T>C mutation. C-Myb activated syncytin-1 promoter activity and expression by binding to mutant 3'-LTRs. Taken together, these data indicate that syncytin-1 overexpression may be an indicator of UCC risk. The 3'-LTR mutations may upregulate syncytin-1 expression, enabling it to participate in UCC tumorigenesis and development by interacting with c-Myb.

Potential relationship between BK virus and renal cell carcinoma.

The objective of the present study was to investigate the potential association between the presence of BK virus (BKV) DNA and mRNA and renal cell carcinoma and bladder transitional cell carcinoma. The formalin-fixed and paraffin-embedded tissue samples were obtained from 50 cancer patients with renal cell carcinoma, 40 cancer patients with bladder transitional cell carcinoma, 45 control patients with the benign renal pathology, and from another 25 control patients with benign bladder pathology. The samples were subjected to nested PCR for detection of BKV DNA and real-time reverse transcription PCR (real-time RT-PCR) for determining mRNA levels of BKV. The results of the nested PCR indicated that 23 (14.3%) of 160 samples were positive for BKV DNA. The relationship between the cancer and the presence of BKV DNA was significant (P < 0.05). The BKV DNA positivity was significantly associated with the histological diagnosis of renal cell carcinoma (P = 0.03), but not with that of bladder transitional cell carcinoma. The results of real-time RT-PCR showed that the mRNA of BKV VP1 was present in 69.5% of the BKV DNA positive samples. The levels of BKV mRNA were significantly higher in the renal cell cancer samples than in the control samples (P < 0.05). The results of the present study confirm the association between BKV and renal cell cancer. The findings also indicated that the presence of BKV DNA resulted in a fivefold increase in the risk of development of renal cell carcinoma.