Molecular and clinical support for a four-tiered grading system for bladder cancer based on the WHO 1973 and 2004 classifications.

Currently, the use of two classification systems for bladder cancer grade is advocated in clinical guidelines because the WHO2004 classification has not been sufficiently validated with biological markers and follow-up. The slides of 325 primary non-muscle invasive bladder cancers from three hospitals were reviewed by one uro-pathologist in two separate sessions for the WHO1973 (G1, G2 and G3) and 2004 (papillary urothelial neoplasm of low malignant potential (LMP), low-grade (LG) and high-grade (HG)) classifications. FGFR3 status was examined with PCR-SNaPshot analysis. Expression of Ki-67, P53 and P27 was analyzed by immuno-histochemistry. Clinical recurrence and progression were determined. We performed validation and cross-validation of the two systems for grade with molecular markers and clinical outcome. Multivariable analyses were done to predict prognosis and pT1 bladder cancer. Grade review resulted in 88 G1, 149 G2 and 88 G3 lesions (WHO1973) and 79 LMP, 101 LG and 145 HG lesions (WHO2004). Molecular validation of both grading systems showed that FGFR3 mutations were associated with lower grades whereas altered expression (Ki-67, P53 and P27) was found in higher grades. Clinical validation showed that the two classification systems were both significant predictors for progression but not for recurrence. Cross-validation of both WHO systems showed a significant stepwise increase in biological (molecular markers) and clinical (progression) potential along the line: G1-LG-G2-HG-G3. The LMP and G1 categories had a similar clinical and molecular profile. On the basis of molecular biology and multivariable clinical data, our results support a four-tiered grading system using the 1973 and 2004 WHO classifications with one low-grade (LMP/LG/G1) category that includes LMP, two intermediate grade (LG/G2 and HG/G2) categories and one high-grade (HG/G3) category.

FGFR3 and P53 characterize alternative genetic pathways in the pathogenesis of urothelial cell carcinoma.

Fibroblast growth factor receptor 3 (FGFR3) and P53 mutations are frequently observed in bladder cancer. We here describe the distribution of FGFR3 mutations and P53 overexpression in 260 primary urothelial cell carcinomas. FGFR3 mutations were observed in 59% and P53 overexpression in 25%. Interestingly, FGFR3 and P53 alterations were mutually exclusive, because they coincided in only 5.7% of tumors. Consequently, we propose that they characterize two alternative genetic pathways in urothelial cell carcinoma pathogenesis. The genetic alterations were reflected in the pathology and the clinical outcome, i.e., FGFR3 mutations were found in low-stage/-grade tumors and were associated with a favorable disease course, whereas P53 alterations were tied to adverse disease parameters.

Molecular grading of urothelial cell carcinoma with fibroblast growth factor receptor 3 and MIB-1 is superior to pathologic grade for the prediction of clinical outcome.

PURPOSE: Fibroblast growth factor receptor 3 (FGFR3) mutations were recently found at a high frequency in well-differentiated urothelial cell carcinoma (UCC). We investigated the relationship between FGFR3 status and three molecular markers (MIB-1, P53, and P27kip1) associated with worse prognosis and determined the reproducibility of pathologic grade and molecular variables. PATIENTS AND METHODS: In this multicenter study, we included 286 patients with primary (first diagnosis) UCC. The histologic slides were reviewed. FGFR3 status was examined by polymerase chain reaction-single strand conformation polymorphism and sequencing. Expression levels of MIB-1, P53, and P27kip1 were determined by immunohistochemistry. Mean follow-up was 5.5 years (range, 0.4 to 18.4 years). RESULTS: FGFR3 mutations were detected in 172 (60%) of 286 UCCs. Grade 1 tumors had an FGFR3 mutation in 88% of patient samples and grade 3 tumors in 16% of patient samples. Conversely, aberrant expression patterns of MIB-1, P53, and P27kip1 were seen in 5%, 2%, and 3% of grade 1 tumors and in 85%, 60%, and 56% of grade 3 tumors, respectively. In multivariate analysis with recurrence rate, progression, and disease-specific survival as end points, the combination of FGFR3 and MIB-1 proved independently significant in all three cases. By using these two molecular markers, three molecular grades (mGs) could be identified: mG1 (mutation; normal expression), favorable prognosis; mG2 (two remaining combinations), intermediate prognosis; and mG3 (no mutation; high expression), poor prognosis. The molecular variables were more reproducible than pathologic grade (85% to 100% v 47% to 61%). CONCLUSION: The FGFR3 mutation represents the favorable molecular pathway of UCC. Molecular grading provides a new, simple, and highly reproducible tool for clinical decision making in UCC patients.

A new system for substaging pT1 papillary bladder cancer: a prognostic evaluation.

Superficially invasive (pT1) papillary urothelial cell carcinomas (UCCs) may run a variable course. Several attempts have been made for the substaging of UCC to identify the clinically aggressive tumors. We present a new substaging system, based on the extent of invasion. From a series of 53 primary pT1 UCC, 24 cases showed invasion of the subepithelial stroma by an invasive front extending more than a maximum length of 0.5 mm (pT1mic), and 29 showed extensively (>0.5 mm) infiltrating UCC (pT1ext). We tested diagnostic reproducibility between 2 pathologists and found 81% agreement. Furthermore, all cases were analyzed for mutations in the fibroblast growth factor receptor 3 (FGFR3) gene, which represents the favorable pathway of urothelial cell carcinogenesis. Mutant FGFR3 was commonly observed in pT1mic UCC (15/24, 63%), but rarely (2/29, 7%) in pT1ext UCC (chi2 test, P < .001). The presence of pT1ext at initial diagnosis proved to be the strongest predictor for progression, also when adjusted for FGFR3 mutation status in a Cox regression model. If confirmed on a larger series of pT1 UCC, this relatively simple and new substaging system for pT1 UCC may prove to be of prognostic value and supportive to clinical decision-making.

The pathologist's mean grade is constant and individualizes the prognostic value of bladder cancer grading.

BACKGROUND: A new grading system for bladder cancer (BCa) was adopted in 2004 to reduce observer variability and provide better prognostic information. OBJECTIVE: We compared the World Health Organization (WHO) 1973 and 2004 systems for observer variability and prognosis. DESIGN, SETTING, AND PARTICIPANTS: Slides of 173 primary non-muscle-invasive BCa were reviewed two times by four pathologists. MEASUREMENTS: Intra- and interobserver variability were assessed using κ statistics. We determined the mean grade (eg, G1/low malignant potential is 1 grade point, G2/low grade is 2 grade points) of the pathologists per grading cycle. Kaplan-Meier analyses were applied for prediction of recurrence and progression. RESULTS AND LIMITATIONS: For WHO 2004 and 1973 grading, the agreement between the pathologists was 39-74% (κ: 0.14-0.58) and 39-64% (κ: 0.15-0.41), respectively. The intraobserver agreement varied from 71% to 88% (κ: 0.55-0.81). The mean grade of a pathologist was constant (difference below 0.1 grade point) irrespective of the grading system. Conversely, mean-grade differences among the pathologists were high, up to 0.7 grade point. The mean grades for the WHO 2004 system were 0.3-0.5 grade point higher than those of WHO 1973. Mean grade distinguished low and high graders among the pathologists and was strongly linked with risk of progression in each grade category. CONCLUSIONS: The variation in mean grade among individual pathologists exceeded the grade shift caused by WHO 2004 grading. Knowledge of the pathologist's mean grade allows a better assessment of the prognostic value of grading. Mean grade has the potential to become a tool for quality assurance in pathology.

Molecular grade (FGFR3/MIB-1) and EORTC risk scores are predictive in primary non-muscle-invasive bladder cancer.

BACKGROUND: The European Organization for Research and Treatment of Cancer (EORTC) risk scores are not validated in an independent patient population. Molecular grade (mG) based on fibroblast growth factor receptor 3 (FGFR3) gene mutation status and MIB-1 expression was proposed as an alternative to pathologic grade in bladder cancer (BCa) [1]. OBJECTIVE: To validate the EORTC risk score and to determine its relation to mG in a series with long-term follow-up as well as to determine reproducibility of pathologic grade and mG. DESIGN, SETTING, AND PARTICIPANTS: In this multicenter study, we included 230 patients with primary non-muscle-invasive BCa (NMIBC). MEASUREMENTS: Four uropathologists reviewed the slides. FGFR3 mutation status was examined by two assays. MIB-1 was assessed by immunohistochemistry. The EORTC risk scores for recurrence and progression were determined. Multivariable analyses were used to find prognostic factors. RESULTS AND LIMITATIONS: Median follow-up was 8.62 yr (interquartile range: 6.6-11.8). FGFR3 mutations were significantly related to favorable disease parameters, whereas altered MIB-1 was frequently seen with pT1, high grade, and high EORTC risk scores. EORTC risk scores were significant in multivariable analyses for recurrence and progression. In multivariable analyses for progression and disease-specific survival, the mG had independent significance. The addition of mG to the multivariable model for progression increased the predictive accuracy from 74.9% to 81.7% (p<0.001; Mantel-Haenszel test). The mG (89%) was more reproducible than the pathologic grade (41-74%). CONCLUSIONS: We validated the EORTC risk scores for primary NMIBC in a clinical and biomarker setting. Next to EORTC risk score, mG proved highly reproducible and predictive. Our long-term results justify an independent prospective analysis of mG and EORTC risk scores.

Frequent FGFR3 mutations in urothelial papilloma.

Activating point mutations in the FGFR3 gene occur frequently in low-grade and low-stage bladder carcinomas, whereas they are rare in high-grade carcinomas. This study investigates the incidence of FGFR3 mutations in 12 urothelial papillomas and 79 pTaG1 tumours which were regraded according to the 1998 WHO/ISUP classification system, resulting in 62 papillary urothelial neoplasms of low malignant potential (PUNs-LMP) and 17 low-grade papillary urothelial carcinomas (LG-PUCs). FGFR3 mutation analysis of 21 ovarian Brenner tumours was also performed. Seventy-seven cases were detected with a mutation in the FGFR3 gene. The mutations were exclusively found in bladder neoplasms. In urothelial papilloma, generally considered a benign lesion, 9/12 (75%) mutations were found. This report is the first to describe a genetic defect in urothelial papilloma. A comparable percentage of mutations was found in PUNs-LMP (85%) and LG-PUCs (88%). No mutations were found in matched normal DNA from bladder tumour patients. The mean follow-up was 5.78 years (range 0.21-17.60 years). Five patients developed high-grade papillary urothelial carcinoma from 2.5 to 12 years after first diagnosis. Two patients died of bladder cancer. The mean number of recurrences (recurrence rate) per year was 0.03, 0.21, and 0.46, respectively, for papilloma, PUN-LMP, and LG-PUC. Urothelial papilloma is a rare lesion with a benign natural behaviour compared with PUN-LMP and LG-PUC of the bladder, but from a molecular perspective, papillomas should be classified together with all well-differentiated urothelial neoplasms.