Recurrence pattern and TP53 mutation in upper urinary tract urothelial carcinoma

MCM4 expression is associated with high-grade histology, tumor progression and poor prognosis in urothelial carcinoma

BACKGROUND

We previously reported Minichromosome maintenance 4 (MCM4) overexpression in gastric cancer. However, the clinicopathological significance of MCM4 in urothelial carcinoma (UC) has not been investigated. To clarify the clinicopathological significance of MCM4 in UC, we investigated MCM4 expression with immunohistochemistry (IHC).

METHODS

We analyzed the expression and distribution of MCM4 in 124 upper tract urothelial carcinoma (UTUC) samples by IHC. Additionally, using 108 urine samples, we analyzed MCM4 Immunocytochemistry (ICC) expression in urine cytology.

RESULTS

In normal urothelium, MCM4 expression was weak or absent. Meanwhile, the strong nuclear expression of MCM4 was observed in UTUC tissues, and it was detected in 77 (62%) of a total of 124 UTUC cases. MCM4-positive UTUC cases were associated with nodular/flat morphology, high grade, high T stage, and poor prognosis. Moreover, MCM4 expression was significantly higher in the invasive front than in the tumor surface. Similar results were also obtained in TCGA bladder cancer cohort. Additionally, MCM4 expression was associated with high expression of Ki-67, HER2, EGFR, and p53 in UTUC. Among representative cancer-related molecules, MCM4 had an independent predictive value for progression-free survival and high-grade UC. ICC for MCM4 was also performed on urine cytology slides and showed that the nuclear expression of MCM4 was more frequently found in UC cells than in non-neoplastic cells. The diagnostic accuracy of urine cytology was improved by combining MCM4 immunostaining with cytology.

CONCLUSION

These results suggest that MCM4 might be a useful predictive biomarker for high-grade histology, tumor progression and poor prognosis in UC. Moreover, ICC for MCM4 might be helpful for UC detection as additional markers in the cytomorphology-based diagnosis.

Clinicopathological significance of TUBB3 in upper tract urothelial carcinoma and possible application in urine cytology

βIII-Tubulin, encoded by the TUBB3 gene, is a microtubule protein. We previously reported that TUBB3 is overexpressed in renal cell carcinoma. We investigated the clinicopathological significance of TUBB3 in upper tract urothelial carcinoma (UTUC) by immunohistochemistry. In normal tissue, TUBB3 expression was weak or absent. In contrast, TUBB3 overexpression was observed in urothelial carcinoma (UC) tissues in 51 (49%) of 103 UTUC cases. TUBB3 overexpression was associated with nodular/flat morphology, high-grade disease, high T stage, and a poor prognosis. Similar results were obtained in The Cancer Genome Atlas bladder cancer cohort. TUBB3 expression was also associated with high Ki-67 labeling index, CD44v9, HER2, EGFR, and p53 expression in UTUC. Among representative cancer-related molecules, TUBB3 was an independent predictor of progression-free survival and high-grade UC. Finally, using urine cytology samples, we analyzed TUBB3 expression by immunocytochemistry. TUBB3 expression was more frequently found in UC cells than in nonneoplastic cells. The diagnostic accuracy of urine cytology was improved when combined with TUBB3 immunostaining. The findings suggest the importance of TUBB3 in tumor progression and its potential application as a biomarker for high-grade disease and the prognosis of UC. Moreover, combination with TUBB3 immunostaining might improve the diagnostic accuracy of urine cytology.

Dual immunocytochemical staining of annexin A10 and p53 in low-grade and papillary urothelial carcinoma contributes to improvement of diagnostic accuracy in urine cytology

BACKGROUND

Urothelial carcinoma (UC) is a common type of human cancer and, although urine cytology is a useful method for identifying high-grade UC (HGUC), its ability to diagnose low-grade UC (LGUC) is limited. The authors previously reported that annexin A10 (ANXA10) expression was strongly linked to both papillary and early stage LGUC and was inversely correlated with p53 expression in upper tract UC (UTUC) and bladder UC. However, it remains largely unknown whether ANXA10 is useful as a diagnostic marker for urine cytology.

METHODS

In this study, the authors used 104 biopsy and 314 urine cytology samples to investigate the efficacy of ANXA10 and p53 expression by immunohistochemistry and immunocytochemistry.

RESULTS

In immunohistochemistry analysis, expression levels of ANXA10 and p53 were either weak or absent in noncancerous tissues, whereas ANXA10 overexpression was observed patients with LGUC, and strong expression of p53 was identified in patients with HGUC. In immunocytochemistry analysis, sensitivity was not good for the detection of UC, especially UTUC, by cytology alone, but it was improved by combining cytology with ANXA10 and p53 to detect both bladder UC and UTUC. Receiver operating characteristic curve analysis also confirmed the diagnostic superiority of cytology combining ANXA10 and p53 for the detection of all UCs, including both HGUC and LGUC (area under the curve, 0.84).

CONCLUSIONS

To the authors' knowledge, this is the first report that the combination of ANXA10 and p53 has potential application as a diagnostic immunomarker for improving the diagnostic accuracy of urine cytology.

Evaluation of molecular signatures in the urinary bladder and upper tract urothelial carcinomas: a prospective controlled clinical study

Background

Urothelial carcinomas (UC) can be either in the upper or in the lower urinary tract or both. Urothelial bladder cancer (UBC) is more common than upper tract urothelial carcinoma (UTUC). This research was designed to study the difference between UBC and UTUC using the molecular pathways including (MAPK/ERK) pathway, cell cycle regulating genes, and oncogenic genes.

Methods

To study the discrepancy between UBC and UTUC, a prospective trial was carried out for 31 radical cystectomy and 19 nephrouretrectomy fresh-frozen specimens of UBC and UTUC patients, respectively. The expression level of mRNA of eight genes namely EGFR, ELK1, c-fos, survivin, TP53, RB1, FGFR3, and hTERT was assessed in normal adjacent tissues, UTUC, and UBC by RT-PCR.

Results

Comparison between UTUC and UBC regarding the expression level of mRNA of the EGFR, ELK1, c-fos, survivin, TP53, and FGFR3 had significant difference (p-value < 0.001), while the expression level of RB1 and hTERT level had no significance. Sensitivity/specificity of EGFR, Elk1, c-fos, survivin, TP53, and FGFR3 was 0.78/0.90, 0.84/0.90, 0.84/0.80, 0.84/0.96, 0.94/0.93, and 0.89/0.93, respectively, to differentiate between UTUC and UBC.

Conclusions

Despite the fact that UTUC and UBC share the same origin, there is a clear evidence that there is a molecular difference between them. This molecular difference could be the reason that UTUC is more aggressive than UBC.

Clinicopathological significance of the overexpression of MUC1 in upper tract urothelial carcinoma and possible application as a diagnostic marker

Mucin 1 (MUC1) overexpression has been reported in many malignancies and is associated with a poor prognosis. However, the clinicopathological significance of MUC1 in upper tract urothelial carcinoma (UTUC) has not been investigated. We analyzed the expression and distribution of MUC1 in UTUC by immunohistochemistry. In normal urothelium, MUC1 expression was observed on the surface of umbrella cells. Meanwhile, the strong expression of MUC1 was observed in cell membranes and cytoplasm in UTUC tissues, and it was detected in 64 (58%) of a total of 110 UTUC cases. MUC1-positive UTUC cases were associated with nodular/flat morphology, high grade, high T stage, and lymphatic and venous invasion and poor prognosis. Additionally, MUC1 expression was associated with high expression of Ki-67, programmed death-ligand 1 (PD-L1), CD44 variant 9 (CD44v9), human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR), and p53 in UTUC. Furthermore, immunocytochemistry for MUC1 on urine cytology slides demonstrated that the strong staining of MUC1 was more frequently found in tumor cells than in nonneoplastic cells. The diagnostic accuracy of urine cytology was improved by combining MUC1 immunostaining with cytology. These results suggest that MUC1 may be a prognostic biomarker in UTUC, and MUC1 exression has a potential application as a diagnostic immunomarker for urine cytology.

Reduced Preoperative Glomerular Filtration Rate Is Associated With Adverse Postoperative Oncological Prognosis in Patients Undergoing Radical Nephroureterectomy for Upper Tract Urothelial Carcinoma: A Retrospective Cohort Study

Objective

To evaluate the association between perioperative estimated glomerular filtration rate (eGFR) and postoperative oncological outcomes in patients with upper tract urothelial carcinoma (UTUC) treated with radical nephroureterectomy (RNU),and to evaluate the effect of sex on this association.

Methods

The medical records of patients with UTUC who underwent RNU between January 2012 and December 2017 at our hospital were retrospectively reviewed. Patients were divided into three groups based on preoperative eGFRs: normal eGFR (>60 mL/min/1.73 m2; n = 179), moderately reduced eGFR (45-60 mL/min/1.73 m2; n = 45), and severely reduced eGFR (≤ 45 mL/min/1.73 m2; n = 36). Statistical analyses were performed to evaluate the prognostic impact of preoperative eGFR on prognosis.

Results

Patient mean age was 66.7 ± 9.6 years, and 47.9% were female. Multivariate regression analysis based on Cox proportional risk models and Kaplan-Meier survival rates showed that lower preoperative eGFR was associated with decreased OS, PFS, and CSS. In the adjusted Cox regression model, patients with normal and moderately reduced eGFRs had a decreased hazard for mortality, with adjusted hazard ratios of 0.13 [95% confidence interval (CI): 0.07-0.26] and 0.36 (95% CI: 0.18-0.73), respectively (P < 0.001). The smooth fitting curve suggested a linear relationship between eGFR and prognostic survival. Additionally, sensitivity subgroup analyses verified an inverse relationship between the reduced eGFR and OS. Women had a lower eGFR and worse oncological outcomes than men. A nomogram for OS was developed based on multivariate analysis with a C-index of 0.754 (95% CI: 0.728-0.779).

Conclusion

Preoperative renal insufficiency is strongly associated with a higher risk of cancer progression and a lower survival probability. It is important to identify preoperative renal insufficiency in patients with UTUC, particularly female patients.

Co-Exposure to Aristolochic Acids I and II Increases DNA Adduct Formation Responsible for Aristolochic Acid I-Mediated Carcinogenicity in Rats

The plant extract aristolochic acid (AA), containing aristolochic acids I (AAI) and II (AAII) as major components, causes aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN), unique renal diseases associated with upper urothelial cancer. Recently (Chemical Research in Toxicology 33(11), 2804–2818, 2020), we showed that the in vivo metabolism of AAI and AAII in Wistar rats is influenced by their co-exposure (i.e., AAI/AAII mixture). Using the same rat model, we investigated how exposure to the AAI/AAII mixture can influence AAI and AAII DNA adduct formation (i.e., AA-mediated genotoxicity). Using ³²P-postlabelling, we found that AA-DNA adduct formation was increased in the livers and kidneys of rats treated with AAI/AAII mixture compared to rats treated with AAI or AAII alone. Measuring the activity of enzymes involved in AA metabolism, we showed that enhanced AA-DNA adduct formation might be caused partially by both decreased AAI detoxification as a result of hepatic CYP2C11 inhibition during treatment with AAI/AAII mixture and by hepatic or renal NQO1 induction, the key enzyme predominantly activating AA to DNA adducts. Moreover, our results indicate that AAII might act as an inhibitor of AAI detoxification in vivo. Consequently, higher amounts of AAI might remain in liver and kidney tissues, which can be reductively activated, resulting in enhanced AAI DNA adduct formation. Collectively, these results indicate that AAII present in the plant extract AA enhances the genotoxic properties of AAI (i.e., AAI DNA adduct formation). As patients suffering from AAN and BEN are always exposed to the plant extract (i.e., AAI/AAII mixture), our findings are crucial to better understanding host factors critical for AAN- and BEN-associated urothelial malignancy.

Aristolochic acid-associated urinary tract cancers: an updated meta-analysis of risk and oncologic outcomes after surgery and systematic review of molecular alterations observed in human studies

BACKGROUND

The risk of primary aristolochic acid (AA)-associated urothelial carcinoma (AA-UC) has been summarized by a 2013-published meta-analysis. Given that additional evidence has been continuously reported by original studies, an updated meta-analysis is needed. Meanwhile, to complete the whole picture, a systematic review of molecular alterations observed in AA-urinary tract cancers (AA-UTC) was also performed.

METHODS

We searched PubMed, Embase and four Chinese databases up to October 2020. Observational studies comparing risk or oncologic outcomes of UTC between patients with and without AA exposure were eligible for systematic review and meta-analysis. Studies investigating molecular alterations in AA-UTC using human tissue samples were eligible for systematic review.

RESULTS

In total, 38 and 20 studies were included in the systematic review and meta-analysis, respectively. Exposure to AA led to an overall increased risks of primary UTC [UC and renal cell carcinoma (RCC)] (OR 6.085, 95% CI 3.045-12.160) and postoperatively recurrent UC (RR 1.831, 95% CI 1.528-2.194). Subgroup analysis of postoperative primary AA-upper tract UC (AA-UTUC) showed increased risks of bladder recurrence (adjusted RR 1.949, 95% CI 1.462-2.597) and contralateral UTUC recurrence (crude RR 3.760, 95% CI 2.225-6.353), worse overall survival (adjusted HR 2.025, 95% CI 1.432-2.865) and worse disease-specific survival (adjusted HR 3.061, 95% CI 1.190-7.872), but no effect on cancer-specific survival (adjusted HR 0.772, 95% CI 0.269-2.215). High mutation load with AA mutational signature presenting largely in the putative driver genes was observed in AA-UTUC. In contrast, AA mutational signature is rarely found in the mutated RCC driver genes and the mutation load in AA-RCC is low. Therefore, AA has different roles in the genesis of UTUC and RCC.

CONCLUSIONS

Implementing effective strategies to completely protect people from exposure to AA is urgently needed. Additionally, more effort should be made in identifying the precise carcinogenic mechanisms of AA to determine the future treatment strategies.

PLAIN LANGUAGE SUMMARY

Risk, recurrence and survival outcomes after surgery and molecular changes possibly involved in the genesis of aristolochic acid-associated urinary tract cancers Background: The association between aristolochic acid (AA) and primary urothelial carcinoma (UC) has been summarized by a 2013-published meta-analysis. Given that additional evidence has been reported in the past 7 years, an updated meta-analysis is needed. Meanwhile, to complete the whole picture, a systematic review of molecular changes possibly involved in AA-mediated urinary tract carcinogenesis was also performed. Methods: We searched PubMed, Embase and four Chinese databases for human studies up to October 2020. Studies comparing the risk of urinary tract cancer (UTC) between patients with and without AA exposure and studies investigating the molecular changes in AA-associated UTC (AA-UTC) using human tissue samples were eligible for inclusion. Thirty-eight studies were finally included. Results: The results showed that exposure to AA was associated with a 6-fold increased risk of primary UTC (UC and renal cell carcinoma, RCC) and a 1.8-fold increased risk of postoperatively recurrent UC. After studies reporting primary AA-upper tract UC (AA-UTUC) were analyzed, a 1.9-fold increased risk of bladder recurrence and a 3.8-fold increased risk of contralateral UTUC recurrence was observed. Additionally, exposure to AA worsened the postoperative survival of patients with UTUC by a 2-fold increased risk of overall death and a 3-fold increased risk of death from other diseases and recurrences. However, there was no effect on death due to cancer. Lastly, AA seemed to play different roles in the etiology of UTUC and RCC based on the observations of different mutation loads and different distributions of AA-induced mutations in AA-UTUC and AA-RCC samples. Conclusions: Implementing effective strategies to completely protect people from exposure to AA is urgently needed. Moreover, more effort should be made in identifying the precise carcinogenic mechanisms of AA-UTC to determine the future treatment strategies.

Significance of p53, p27, Ki-67, E-cadherin, and HER2 expression in upper urinary tract urothelial carcinoma

BACKGROUND

The study investigated the expression and the clinicopathological significance of p53, p27, Ki-67, E-cadherin, and HER2 in upper urinary tract urothelial carcinomas (UTUC) from Tunisian patients. We performed a retrospective study of 66 UTUC. Main clinicopathological features were reported. The expression of p53, p27, Ki-67, E-cadherin, and HER2 was investigated by immunohistochemistry on whole tissue section.

RESULTS

Expression of p53, Ki-67, p27, E-cadherin, and HERE2 was reported in 36.4%, 69.7%, 90.9%, 100%, and 0% of cases, respectively. p53 expression was associated with stage (p = 0.001), positive surgical margin (p = 0.005), and shorter recurrence-free survival (RFS; Log Rank test, p = 0.026). Ki-67 and p27 expression was associated with stage (p < 0.001 and p = 0.001, respectively) and grade (p < 0.001 and p = 0.001, respectively). Using Kaplan-Meier test, the positive surgical margin was associated with shorter RFS compared to free surgical margin (Log Rank test, p = 0.031). Moreover, in univariate Cox regression analysis, surgical margin (p = 0.041; HR 0.325, 95% CI 0.110-0.956) and p53 expression (p = 0.035; HR 0.328, 95% CI 0.116-0.925) were the significant factors associated with RFS.

CONCLUSIONS

Together, our findings suggest that positive surgical margin and p53 expression were potential prognostic factors of UTUC since both were associated with shorter RFS in Tunisian patients.

Clinicopathologic characteristics and prognosis of upper tract urothelial carcinoma complicated with aristolochic acid nephropathy after radical nephroureterectomy

Background

The purpose of this study was to identify the clinicopathologic characteristics and prognosis of upper tract urothelial carcinoma (UTUC) patients complicated with aristolochic acid nephropathy(AAN) after radical nephroureterectomy (RNU).

Methods

The clinical data of 42 UTUC patients with AAN (AAN group) and 238 UTUC patients without AAN (Non-AAN group) were retrospectively reviewed. All patients received a RNU with excision of bladder cuff. Demographic and clinical data, including preoperative indexes, intraoperative indexes and surgical outcomes were compared.

Results

There were no significant differences in age, tumor location, surgery approach, tumor pathologic grade, stage, the mean operative time and estimated blood loss between the two groups (all p > 0.05). There were more female patients in the AAN group (p < 0.001), and 57.1% were high grade tumors. The AAN group showed a higher complications rate (p = 0.003). The median follow-up time was 43.2 months. The AAN group showed a worse estimated 5-year overall survival rate (35.1% vs. 63.0%, p = 0.014), however, no significant difference was found between the two groups with regard to disease specific survival (63.5% vs. 81.5%, p = 0.091). Multivariate binary logistic regression analysis showed that AAN was an independent factor related with overall and disease specific survival. 38.9% of all patients experienced any types of recurrence, and the estimated 5-year recurrence-free survival rate was lower in the AAN group (37.1% vs. 63.7%, p = 0.001). In the comparison of subgroups stratified by recurrence type, the AAN group had a higher intravesical (p = 0.030) and contralateral recurrence rate (p = 0.040).

Conclusion

UTUC with AAN occurred more frequently in female patients who were more likely to develop high-grade tumors. However, these patients showed a worse overall survival and a lower recurrence-free survival rate than the other patients. AA-related UTUC might be associate with an increased risk of intravesical and contralateral recurrence after RUN.

Aristolochic Acid Affects Upper Tract Urothelial Cancer Behavior through the MAPK Pathway

The prevalence of upper tract urothelial carcinoma (UTUC) in Taiwan is relatively higher than thatin Western countries. Aristolochic acid (AA), which is widely used in traditional Chinese herbology, is now recognized to be one of the carcinogens for UTUC. Numerous UTUC patients have chronic kidney diseases or end-stage renal diseases; however, little literature hasreported on theoncogenic pathway of AA-related UTUC. The aim of our study was to identify the potential target treatment for AA-related UTUC. Here, we established an AA pre-exposure followed bya 3-methylcholanthrene (MCA) stimulus tumorigenic cell model. We not only demonstrated that AA pre-exposure MCA stimulus tumorigenic cells have more behaviors of cell migration and invasion by enhancing the metalloproteinases (MMP) activity, which is compatible with clinical findings of AA-related UTUC, but we also validated that AA pre-exposure MCA stimulus tumorigeniccells could be activated through the mitogen-activated protein kinases (MAPK) pathway. We further dissected the route of the MAPK pathway and found that the p38 and extracellular signal regulated kinases (ERK) sub-pathways might play essential roles in AA pre-exposure urothelial cancer cell lines. This consequence was also corroborated with a tissue study in AA-exposed patients.

Recognition of the toxicity of aristolochic acid

WHAT IS KNOWN AND OBJECTIVE

Aristolochic acid (AA) is an abundant compound in Aristolochia plants and various natural herbs. In the 1990s, a slimming formula used in Belgium that contains Aristolochia fangchi was reported to cause kidney damage and bladder cancer, and aristolochic acid nephropathy (AAN) is now well recognized worldwide. In October 2017, researchers reported an AA signature that is closely associated with hepatocellular carcinoma (HCC) worldwide.

COMMENT

There are differing opinions on the toxicity of AA, and different countries have taken different measures to address the issue. There is a lack of clarity on the causal role of AA in hepatocarcinogenesis and on the potential underlying mechanisms for the reported nephrotoxicity and carcinogenicity. The toxicity of AA differs depending on gender and age, and other risk factors that could explain the variability in the toxicity of AA remain to be identified.

WHAT IS NEW AND CONCLUSION

Whether preparations containing AA, such as many Chinese medicines, should be used remains controversial, and this issue warrants further investigation before definite conclusions can be drawn.

Impact of aristolochic acid exposure on oncologic outcomes of upper tract urothelial carcinoma after radical nephroureterectomy

Objective

To investigate the effect of aristolochic acids (AA) exposure, including exposure duration and years since last exposure, on oncologic outcomes of patients with upper tract urothelial carcinoma (UTUC) after radical nephroureterectomy (RNU).

Methods

We retrospectively collected clinicopathologic and AA exposure variables for 942 UTUC patients treated with RNU between 1999 and 2014 in a high-volume center of China. AA exposure duration was categorized as (>3 vs ≤3 years) and time since last AA exposure to surgery as (>5 vs ≤5 years).

Results

A total of 856 patients (90.9%) had none or possible AA exposure and 86 patients (9.1%) had credible AA exposure history. Among the 86 patients, 57 (66.3%) had AA exposure for ≤3 years and 29 (33.7%) had exposure for >3 years. The median follow-up duration was 60 months. By multivariate analysis, AA exposure history was significantly associated with cancer specific survival (hazard ratio [HR]: 0.43, p=0.02), intravesical recurrence (IVR) (HR: 2.25, p<0.001) and contralateral UTUC recurrence (HR: 2.71, p=0.001). After adjusted for the effects of standard clinicopathologic characteristics, exposure duration was independent risk factor for subsequent IVR (exposure duration ≤3 years vs none/possible AA, HR: 1.87, p=0.009; exposure duration >3 years vs none/possible AA, HR: 3.07, p<0.001), but not for cancer-specific survival (p=0.06). Also, of those patients who had AA exposure, those having exposure within 5 years prior to RNU did not differ from patients having last exposure >5 years ago regarding cancer specific mortality (p=0.67) and IVR (p=0.54).

Conclusion

AA exposure was associated with worse cancer-specific survival, higher rate of IVR and contralateral UTUC recurrence of UTUC treated with RNU. The association between AA exposure and IVR seems to be time-dependent. Exposure cessation >5 years prior to RNU cannot mitigate the impact of AA on the UTUC prognosis.

DNA Adducts Formed by Aristolochic Acid Are Unique Biomarkers of Exposure and Explain the Initiation Phase of Upper Urothelial Cancer

Aristolochic acid (AA) is a plant alkaloid that causes aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN), unique renal diseases frequently associated with upper urothelial cancer (UUC). This review summarizes the significance of AA-derived DNA adducts in the aetiology of UUC leading to specific A:T to T:A transversion mutations (mutational signature) in AAN/BEN-associated tumours, which are otherwise rare in individuals with UCC not exposed to AA. Therefore, such DNA damage produced by AA-DNA adducts is one rare example of the direct association of exposure and cancer development (UUC) in humans, confirming that the covalent binding of carcinogens to DNA is causally related to tumourigenesis. Although aristolochic acid I (AAI), the major component of the natural plant extract AA, might directly cause interstitial nephropathy, enzymatic activation of AAI to reactive intermediates capable of binding to DNA is a necessary step leading to the formation of AA-DNA adducts and subsequently AA-induced malignant transformation. Therefore, AA-DNA adducts can not only be utilized as biomarkers for the assessment of AA exposure and markers of AA-induced UUC, but also be used for the mechanistic evaluation of its enzymatic activation and detoxification. Differences in AA metabolism might be one of the reasons for an individual’s susceptibility in the multi-step process of AA carcinogenesis and studying associations between activities and/or polymorphisms of the enzymes metabolising AA is an important determinant to identify individuals having a high risk of developing AA-mediated UUC.

Balkan endemic nephropathy: an update on its aetiology

Balkan endemic nephropathy (BEN) is a unique, chronic renal disease frequently associated with upper urothelial cancer (UUC). It only affects residents of specific farming villages located along tributaries of the Danube River in Bosnia-Herzegovina, Croatia, Macedonia, Serbia, Bulgaria, and Romania where it is estimated that ~100,000 individuals are at risk of BEN, while ~25,000 have the disease. This review summarises current findings on the aetiology of BEN. Over the last 50 years, several hypotheses on the cause of BEN have been formulated, including mycotoxins, heavy metals, viruses, and trace-element insufficiencies. However, recent molecular epidemiological studies provide a strong case that chronic dietary exposure to aristolochic acid (AA) a principal component of Aristolochia clematitis which grows as a weed in the wheat fields of the endemic regions is the cause of BEN and associated UUC. One of the still enigmatic features of BEN that need to be resolved is why the prevalence of BEN is only 3-7 %. This suggests that individual genetic susceptibilities to AA exist in humans. In fact dietary ingestion of AA along with individual genetic susceptibility provides a scenario that plausibly can explain all the peculiarities of BEN such as geographical distribution and high risk of urothelial cancer. For the countries harbouring BEN implementing public health measures to avoid AA exposure is of the utmost importance because this seems to be the best way to eradicate this once mysterious disease to which the residents of BEN villages have been completely and utterly at mercy for so long.