1 Introduction
Upper urinary tract urothelial carcinoma (UTUC) is a relatively rare urologic malignancy; however, UTUC has a relatively high recurrence rate and affected patients exhibit poor prognosis, especially those with advanced disease.[1–3] [1] [4,5] [6–10]
E-cadherin is a transmembrane glycoprotein expressed in all normal epithelia and is the prime mediator of cell–cell adhesion.[11] [12,13] [14,15] [16–18] [19]
Although decreased expression of E-cadherin is correlated with poor prognosis in patients with UTUC, many studies on E-cadherin have not yet been conducted.[20–23]
2 Materials and methods
2.1 Data sources and search strategy
This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.[24]
2.2 Study eligibility
We included papers that met the following criteria in the meta-analysis:
(1) human research;
(2) patients who underwent radical nephroureterectomy (RNU) for UTUC;
(3) studies that assessed E-cadherin protein expression;
(4) availability of Kaplan–Meier/uni- or multivariate Cox proportional hazard model results to estimate the hazard ratios (HRs) and their 95% confidence intervals (CIs).
In addition, we excluded papers with the following criteria:
(1) commentaries, case reports, reviews, letters, and articles that did not provide raw data;
(2) non-English articles;
(3) studies that did not examine E-cadherin expression, clinical parameters, and survival outcomes;
(4) papers that did not present sufficient data for obtaining HRs and 95% CIs;
(5) patients with UTUC who underwent segmentectomy or nephron-sparing surgery.
If there were duplications of study populations or analyses of repeated data, only the largest or most recent article was chosen for meta-analysis.
Initial screening of the relevant articles was performed by 2 reviewers (BST and JHK) based on the titles and abstracts of all the available literature. Two other reviewers (CK and CWJ) independently checked full-text articles to determine whether they met the inclusion criteria of our meta-analysis. If there were discrepancies between the 2 reviewers, discussion with another reviewer (HHK) was undertaken until discrepancies were resolved.
2.3 Data extraction and quality assessments
Two reviewers (BST and JHK) independently extracted and crosschecked the required information from all the eligible studies. We extracted the following relevant data: publication data, including author names and the year of publication of the study, study design, origin of the studied population, pathologic UTUC stage, sample size, sex, age of studied patients, cut-off value of E-cadherin expression, follow-up period, and estimated HRs of E-cadherin expression for overall survival (OS), recurrence-free survival (RFS), and cancer-specific survival (CSS), as well as their 95% CIs.
We used the REporting recommendations for tumor MARKer prognostic studies (REMARK) guidelines and quality scales to perform quality assessment. Quality scales and the included study parameters are as follows[25]
(1) sufficient description of the characteristics of the study patients and tumor characteristics, including inclusion and exclusion criteria;
(2) statement of the method of data acquisition, whether prospective or retrospective;
(3) sufficient description of E-cadherin expression measurement;
(4) clear study endpoint;
(5) sufficient description of enrolled patients’ follow-up period;
(6) identification of patients lost to follow-up or not available for statistical analysis. Scores ranged from 0 (studies of the lowest quality) to 8 (studies of the highest quality).
2.4 Statistical analysis
We performed a meta-analysis to quantitatively summarize the overall prognostic value of E-cadherin expression. Pooled HRs and 95% CIs were used to examine the effect of reduced E-cadherin expression on the prognosis and clinicopathological features of UTUC, respectively. If the 95% CIs did not overlap, an HR of greater than 1 indicated that reduced expression of E-cadherin was associated with worse prognosis. If explicit survival data were not provided, we calculated survival outcomes based on the available numerical data using methods described by Parmer et al.[26] I 2 tests, which describe the percentage of total variation across studies caused by heterogeneity rather than by chance, were used to evaluate heterogeneity between studies. A Q-test with a P value of <.05 or an I 2 value of >50% indicated the presence of significant heterogeneity across the selected studies.[27] P value of <.05 was considered statistically significant.[28,29] P < .05. We used RevMan 5.0 statistical software (the Cochrane Collaboration, Copenhagen) to perform the meta-analysis. Publication bias was analyzed using R statistical software version 2.13.0 (R Development Core Team, Vienna, Austria; http://www.r-project.org
3 Result
3.1 Literature search results
Table 1 shows individual data on the characteristics of the selected studies. Three studies were conducted in Japan, 1 study was performed in France, and the remaining studies were multinational from Europe, the USA, and Austria. The studies were published between 2005 and 2017 and the patient recruitment periods ranged from 1981 to 2010. Figure 1 shows the PRISMA flow chart describing the literature search and selection of papers.
Table 1: Characteristics of the eligible studies.
Figure 1: PRISMA statement flow diagram illustrating the search strategy used for the meta-analysis.
3.2 Study characteristics
The characteristics of the selected studies are described in Tables 1 and 2 . The total number of patients from all the studies was 1014 (individual studies range, 59–678; median, 61). Among the selected studies, Favaretto et al and Abufaraj et al employed the same retrospective cohort of the international UTUC collaboration.[30] Tables 3–5 , respectively). All the studies evaluated E-cadherin expression using immunohistochemistry (IHC) staining. Reduced E-cadherin expression was defined using different cut-off values in each study; thus, we classified all the patients on the basis of their original studies’ results.
Table 2: Pathologic characteristics from the eligible studies.
Table 3: Estimation of the hazard ratio for recurrence-free survival.
Table 4: Estimation of the hazard ratio for cancer-specific survival.
Table 5: Estimation of the hazard ratio for overall survival.
3.3 Outcomes from eligible studies
The results of the meta-analysis are presented in Figures 2–4 . Overall, the pooled HR for RFS was 0.69 (95% CI, 0.44–1.09), suggesting that reduced E-cadherin expression does not correlate with poor prognosis for UTUC and there was significant heterogeneity between the studies (I 2 = 63%, P = .04). In addition, there was no statistically significant association between reduced E-cadherin expression and CSS in patients with UTUC (pooled HR 1.40; 95% CI, 0.66–2.96, I 2 = 54%, P = .11) (Fig. 3 ). In addition, a meta-analysis of the 3 studies evaluating the association of reduced E-cadherin expression and OS found that reduced E-cadherin expression was not significantly associated with worse outcomes, with a pooled HR of 0.68 (95% CI, 0.32–1.16) with significant heterogeneity (I 2 = 80%, P = .007) (Fig. 4 ).
Figure 2: Forest plots of recurrence-free survival (RFS) by reduced E-cadherin. A: The horizontal lines correspond to the study-specific hazard ratios (HRs) and 95% confidence interval (CIs), respectively. The area of the squares reflects the study-specific weights. The diamond represents the pooled results of HRs and 95% CIs. B: The Begg test funnel plots for publication bias. Each point represents a separate study of the indicated association. The vertical line represents the mean effects size.
Figure 3: Forest plots of cancer-specific survival (CSS) by reduced E-cadherin. A: The horizontal lines correspond to the study-specific hazard ratios (HRs) and 95% confidence intervals (CIs), respectively. The area of the squares reflects the study-specific weights. The diamond represents the pooled results of HRs and 95% CIs. B: The Begg test funnel plots for publication bias. Each point represents a separate study of the indicated association. The vertical line represents the mean effects size.
Figure 4: Forest plots of overall survival (OS) by reduced E-cadherin. A: The horizontal lines correspond to the study-specific hazard ratios (HRs) and 95% confidence intervals (CIs), respectively. The area of the squares reflects the study-specific weights. The diamond represents the pooled results of HRs and 95% CIs. B: The Begg test funnel plots for publication bias. Each point represents a separate study of the indicated association. The vertical line represents the mean effects size.
3.4 Publication bias
Obvious asymmetry was not evident in the funnel plots of any contrast (Figs. 2–4 ). Begg test (P value) and Egger tests (P value, intercept with corresponding 95% CI), as well as funnel plots, were used to assess publication bias in this meta-analysis. All the P values for Begg test and Egger test for RFS, CSS, and OS were >.05, presenting statistical evidence of the funnel plots’ symmetry. These results suggested that publication bias was not detected in this meta-analysis.
4 Discussion
E-cadherin is a known tumor suppressor that plays a central role in suppressing the invasive phenotype of cancer cells, and many researchers have demonstrated that reduced E-cadherin expression is emerging as a factor of poor prognosis in various types of carcinomas.[31–33] [19,20,34] [23] [35] [36]
Consequently, E-cadherin has emerged as a valuable prognostic indicator and potential therapeutic target for urothelial carcinoma. Indeed, a recent meta-analysis presented that reduced E-cadherin expression is associated with poor prognosis and advanced clinicopathological characteristics in UBC.[19]
To avoid bias caused by the different methods used to evaluate E-cadherin expression, we only included papers that reported on IHC-based evaluation methods in our meta-analysis. Our final analysis included clinical outcomes from 6 eligible studies including a total of 1014 patients with UTUC. Among the eligible studies, studies by Favaretto et al and Abufaraj et al employed the same multicenter retrospective cohort; however, there were differences in the primary endpoints between the 2 studies. Thus, we used the results acquired by Favaretto et al to analyze CSS and RFS and the results acquired by Abufaraj et al to analyze OS. Our findings showed that there was no association between reduced expression of E-cadherin and UTUC prognosis. These findings do not correspond with the results of previous meta-analyses on UBC, which demonstrate that reduction of E-cadherin expression is a prognostic factor.[19]
Many researchers have shown their interest in studying the effect of E-cadherin expression on the prognosis of patients with UTUC. Nakanishi et al first presented that reduced E-cadherin expression is associated with higher tumor stage and grade in UTUC.[34] [37] [22] [20,21,23,38] [37]
Although many studies have reported that reduced expression of E-cadherin is associated with adverse clinicopathological features, the reason for the lack of independent prognostic value is presumed to be as follows. First, there was no standardization of the E-cadherin IHC method in each study. The use of different primary antibody sources and different antibody dilution ratios in each study could have resulted in different conclusions. If tissue microarrays with standardized staining protocols and automated scoring systems based on bright-field microscopy imaging coupled with advanced color detection software are developed, they might be of aid to overcome the above limitations.[23] [39]
As mentioned above, E-cadherin was first revealed to be an independent marker in a subsequent multivariate analysis in 2005.[37] [10,34,38,40] [41] [42] [43]
Although there is no correlation between E-cadherin expression and UTUC prognosis in this analysis, the contributions of our study are as follows. To the best of our knowledge, our study is the first systematic review and meta-analysis to evaluate the prognostic value of E-cadherin expression with a focus on survival benefits in patients with UTUC, which may help clinicians plan subsequent treatments after radical surgery. Second, in the present meta-analysis, studies reporting HRs of cumulative survival rates were qualitatively summarized using standard meta-analysis techniques. In addition, our study is mainly based on adjusted estimates, but no statistical significance was found for all three endpoints: RFS, CSS, and OS.
Despite the highlights mentioned above, there are still some limitations in our meta-analysis that should be pointed out. First, most of the included studies were of a retrospective design. Second, as mentioned above, the criteria to define normal and reduced expression of E-cadherin were not standardized across different studies, which might be the potential cause of heterogeneity. Thus, a more unified scoring criterion based on IHC methods should be defined in the future.[19]
5 Conclusions
Our meta-analysis reveals that reduced E-cadherin expression in UTUC may not correlate with disease prognosis. However, to avoid bias in future studies, we recommend standardization of E-cadherin expression cut-off values and providing HR values with their 95% CIs. Our results should be validated by more comprehensive investigations with prospective, large-population studies.
Author contributions
Conceptualization: Ja Hyeon Ku.
Data curation: Bum Sik Tae, Chang Wook Jeong, Hyeon Hoe Kim, Ja Hyeon Ku.
Formal analysis: Cheol Kwak, Hyeon Hoe Kim, Ja Hyeon Ku.
Funding acquisition: Ja Hyeon Ku.
Investigation: Bum Sik Tae, Cheol Kwak, Ja Hyeon Ku.
Methodology: Hyeon Hoe Kim, Ja Hyeon Ku.
Project administration: Cheol Kwak.
Supervision: Bum Sik Tae, Chang Wook Jeong, Cheol Kwak, Hyeon Hoe Kim, Ja Hyeon Ku.
Validation: Ja Hyeon Ku.
Writing – original draft: Bum Sik Tae.
Writing – review & editing: Cheol Kwak, Hyeon Hoe Kim, Ja Hyeon Ku.
Bum Sik Tae orcid: 0000-0003-2963-7366.
References
[1]. Roupret M, Babjuk M, Comperat E, et al. European association of urology guidelines on upper urinary tract urothelial carcinoma: 2017 update. Eur Urol 2017;73:111–22.
[2]. Hall MC, Womack S, Sagalowsky AI, et al. Prognostic factors, recurrence, and survival in transitional cell carcinoma of the upper urinary tract: a 30-year experience in 252 patients. Urology 1998;52:594–601.
[3]. Ploussard G, Xylinas E, Lotan Y, et al. Conditional survival after radical nephroureterectomy for upper tract carcinoma. Eur Urol 2015;67:803–12.
[4]. Lughezzani G, Burger M, Margulis V, et al. Prognostic factors in upper urinary tract urothelial carcinomas: a comprehensive review of the current literature. Eur Urol 2012;62:100–14.
[5]. Chromecki TF, Cha EK, Fajkovic H, et al. The impact of tumor multifocality on outcomes in patients treated with radical nephroureterectomy. Eur Urol 2012;61:245–53.
[6]. Yamamoto Y, Matsuyama H, Kawauchi S, et al. Overexpression of polo-like kinase 1 (PLK1) and chromosomal instability in bladder cancer. Oncology 2006;70:231–7.
[7]. Yamamoto Y, Matsuyama H, Kawauchi S, et al. Biological characteristics in bladder cancer depend on the type of genetic instability. Clin Cancer Res 2006;12:2752–8.
[8]. Wallerand H, Robert G, Pasticier G, et al. The epithelial-mesenchymal transition-inducing factor TWIST is an attractive target in advanced and/or metastatic bladder and prostate cancers. Urol Oncol 2010;28:473–9.
[9]. van der Horst G, Bos L, van der Pluijm G. Epithelial plasticity, cancer stem cells, and the tumor-supportive stroma in bladder carcinoma. Mol Cancer Res 2012;10:995–1009.
[10]. Kosaka T, Kikuchi E, Mikami S, et al. Expression of snail in upper urinary tract urothelial carcinoma: prognostic significance and implications for tumor invasion. Clin Cancer Res 2010;16:5814–23.
[11]. Smith ME, Pignatelli M. The molecular histology of neoplasia: the role of the cadherin/catenin complex. Histopathology 1997;31:107–11.
[12]. van Roy F, Berx G. The cell-cell adhesion molecule E-cadherin. Cell Mol Life Sci 2008;65:3756–88.
[13]. Mani SA, Guo W, Liao MJ, et al. The epithelial-mesenchymal transition generates cells with properties of stem cells. Cell 2008;133:704–15.
[14]. Fujisawa M, Miyazaki J, Takechi Y, et al. The significance of E-cadherin in transitional-cell carcinoma of the human urinary bladder. World J Urol 1996;14(Suppl 1):S12–15.
[15]. Popov Z, Gil-Diez de Medina S, Lefrere-Belda MA, et al. Low E-cadherin expression in bladder cancer at the transcriptional and protein level provides prognostic information. Br J Cancer 2000;83:209–14.
[16]. Raspollini MR, Luque RJ, Menendez CL, et al. T1 high-grade bladder carcinoma outcome: the role of p16, topoisomerase-IIalpha, survivin, and E-cadherin. Hum Pathol 2016;57:78–84.
[17]. Breyer J, Gierth M, Shalekenov S, et al. Epithelial-mesenchymal transformation markers E-cadherin and survivin predict progression of stage pTa urothelial bladder carcinoma. World J Urol 2016;34:709–16.
[18]. Mitra AP, Castelao JE, Hawes D, et al. Combination of molecular alterations and smoking intensity predicts bladder cancer outcome: a report from the Los Angeles Cancer Surveillance Program. Cancer 2013;119:756–65.
[19]. Xie Y, Li P, Gao Y, et al. Reduced E-cadherin expression is correlated with poor prognosis in patients with bladder cancer: a systematic review and meta-analysis. Oncotarget 2017;8:62489–99.
[20]. Muramaki M, Miyake H, Terakawa T, et al. Expression profile of E-cadherin and N-cadherin in urothelial carcinoma of the upper urinary tract is associated with disease recurrence in patients undergoing nephroureterectomy. Urology 2011;78:1443e1447-1412.
[21]. Abufaraj M, Moschini M, Soria F, et al. Prognostic role of expression of N-cadherin in patients with upper tract urothelial carcinoma: a multi-institutional study. World J Urol 2017;35:1073–80.
[22]. Kashibuchi K, Tomita K, Schalken JA, et al. The prognostic value of E-cadherin, alpha-, beta-, and gamma-catenin in urothelial cancer of the upper urinary tract. Eur Urol 2006;49:839–45. discussion 845.
[23]. Favaretto RL, Bahadori A, Mathieu R, et al. Prognostic role of decreased E-cadherin expression in patients with upper tract urothelial carcinoma: a multi-institutional study. World J Urol 2017;35:113–20.
[24]. Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med 2009;151:264–9. w264.
[25]. McShane LM, Altman DG, Sauerbrei W, et al. Reporting recommendations for tumor marker prognostic studies (REMARK). J Natl Cancer Inst 2005;97:1180–4.
[26]. Parmar MK, Torri V, Stewart L. Extracting summary statistics to perform meta-analyses of the published literature for survival endpoints. Stat Med 1998;17:2815–34.
[27]. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177–88.
[28]. Begg CB, Mazumdar M. Operating characteristics of a rank correlation test for publication bias. Biometrics 1994;50:1088–101.
[29]. Egger M, Davey Smith G, Schneider M, et al. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997;315:629–34.
[30]. Mathieu R, Klatte T, Margulis V, et al. Survivin is not an independent prognostic factor for patients with upper tract urothelial carcinoma: a multi-institutional study. Urol Oncol 2015;33:495e415-422.
[31]. Li Z, Yin S, Zhang L, et al. Prognostic value of reduced E-cadherin expression in breast cancer: a meta-analysis. Oncotarget 2017;8:16445–55.
[32]. Luo SL, Xie YG, Li Z, et al. E-cadherin expression and prognosis of oral cancer: a meta-analysis. Tumour Biol 2014;35:5533–7.
[33]. Ren X, Wang J, Lin X, et al. E-cadherin expression and prognosis of head and neck squamous cell carcinoma: evidence from 19 published investigations. Onco Targets Ther 2016;9:2447–53.
[34]. Nakanishi K, Kawai T, Torikata C, et al. E-cadherin expression in upper-urinary-tract carcinoma. Int J Cancer 1997;74:446–9.
[35]. Frixen UH, Behrens J, Sachs M, et al. E-cadherin-mediated cell-cell adhesion prevents invasiveness of human carcinoma cells. J Cell Biol 1991;113:173–85.
[36]. Bryan RT, Tselepis C. Cadherin switching and bladder cancer. J Urol 2010;184:423–31.
[37]. Fromont G, Roupret M, Amira N, et al. Tissue microarray analysis of the prognostic value of E-cadherin, Ki67, p53, p27, survivin and MSH2 expression in upper urinary tract transitional cell carcinoma. Eur Urol 2005;48:764–70.
[38]. Matsumoto H, Munemori M, Shimizu K, et al. Risk stratification using Bmi-1 and Snail expression is a useful prognostic tool for patients with upper tract urothelial carcinoma. Int J Urol 2016;23:1030–7.
[39]. Shiozaki H, Tahara H, Oka H, et al. Expression of immunoreactive E-cadherin adhesion molecules in human cancers. Am J Pathol 1991;139:17–23.
[40]. Jeon HG, Jeong IG, Bae J, et al. Expression of Ki-67 and COX-2 in patients with upper urinary tract urothelial carcinoma. Urology 2010;76:513e517-512.
[41]. Woodford R, Ranasinghe W, Aw HC, et al. Trends in incidence and survival for upper tract urothelial cancer (UTUC) in the state of Victoria--Australia. BJU Int 2016;117(Suppl 4):45–9.
[42]. Roupret M, Azzouzi AR, Cussenot O. Microsatellite instability and transitional cell carcinoma of the upper urinary tract. BJU Int 2005;96:489–92.
[43]. Yates DR, Roupret M, Drouin SJ, et al. Genetic polymorphisms on 8q24.1 and 4p16.3 are not linked with urothelial carcinoma of the bladder in contrast to their association with aggressive upper urinary tract tumours. J Urol 2013;31:53–9.
