[Current knowledge in molecular pathology of urothelial cancer]

The therapeutic and prognostic implications of molecular biomarkers in urothelial carcinoma

Urothelial cell carcinoma (UCC) of the bladder and upper urinary tract is a heterogeneous disease with distinct biologic features resulting in different clinical behaviors. Bladder cancer (BC) is classified into non-muscle invasive BC (NMIBC) and muscle invasive BC (MIBC). NMIBC is associated with high recurrence rates and risk of progression to invasive disease, whereas MIBC is complicated by systemic recurrence after radical cystectomy because of the limited efficacy of available therapies. UCC of the upper urinary tract (UUT-UCC) is a rare but aggressive urologic cancer characterized by multifocality, local recurrence, and metastasis. Conventional histopathologic evaluation of UCC, including tumor stage and grade, cannot accurately predict the behavior of BC and UUT-UCC. Recent clinical and preclinical studies aimed at understanding the molecular landscape of UCC have provided insight into molecular subtyping, inter- or intratumoral heterogeneity, and potential therapeutic targets. Combined analysis of molecular markers and standard pathological features may improve risk stratification and help monitor tumor progression and treatment response, ultimately improving patient outcomes. This review discusses prognostic and therapeutic biomarkers for BC and UUT-UCC, and describes recent advances in molecular stratification that may guide prognosis, patient stratification, and treatment selection.

Snail immunohistochemical overexpression correlates to recurrence risk in non-muscle invasive bladder cancer: results from a longitudinal cohort study

The current WHO/ISUP classification and grading system subdivides urothelial tumours into prognostically distinct categories. Understanding the molecular pathways involved in bladder cancer development can improve patient stratification and management. This study aims to investigate the relationship between Snail, Slug and E-cadherin expressions and clinico-pathological features of non-muscle invasive bladder carcinoma (NMIBC). All patients attending the same urological centre from January to May 2002, who were pathologically diagnosed with NMIBC, were enrolled in this longitudinal cohort study. E-cadherin, Snail and Slug protein expressions were assessed by immunohistochemical analysis and compared with follow-up data. The main outcome measures were recurrence and progression rates. The cohort under investigation included 43 patients (38 men and 5 women, mean age 67.7 ± 10.6 years). High-grade (HG) carcinomas were 20/43, with 10 invasive cases (pT1). Low-grade (LG) carcinomas were 23/43, with no invasive cases (pTa). Among the eight HGpTa cases with recurrence, strong Snail expression was detected in six (75%). Out of the 17 LGpTa patients who experienced recurrence, 12 (70.6%) showed strong positivity for Snail. Among the 10 HGpT1 cases, recurrence was observed in 4, of which, 3 (75%) stained intensely for Snail. The Kaplan-Meier curves showed significantly different recurrence rates for patients with strong or weak Snail reactivity (p = 0.027). E-cadherin and Slug expression did not correlate with any of the parameters considered. On multivariate analysis, Snail expression was recognised as an independent prognostic factor for tumour recurrence (p = 0.003). In our study population, Snail immunohistochemical overexpression proved to be related to tumour recurrence in patients affected by NMIBC.

Piwil 2 expression is correlated with disease-specific and progression-free survival of chemotherapy-treated bladder cancer patients

Piwi-like 2 (Piwil 2) belongs to the family of Argonaute genes/proteins. The expression of Piwil 2 is associated with stem cells. A role in tumorigenesis and/or tumor progression is proposed for different cancers but not yet for bladder cancer (BCa). We investigated the Piwil 2 expression by immunohistochemistry in a cohort of 202 BCa patients treated by cystectomy and adjuvant chemotherapy. The association between Piwil 2 expression and disease-specific (DSS) or progression-free survival (PFS) was calculated using Kaplan Meier analyses and univariate/multivariate Cox's regression hazard models.In a multivariate Cox's regression, Piwil 2 expression, either in the cytoplasm or the nucleus, was significantly associated with DSS and PFS. A weak cytoplasmic staining pattern was associated with poor DSS and tumor progression (RR=2.7; P=0.004 and RR=2.4; P=0.027). Likewise,, absent nuclear Piwil 2 immunoreactivity was associated with poor DSS and tumor progression (RR=2.3; P=0.023 and RR=2.2; P=0.022). BCa patients whose tumors exhibited a combination of weak cytoplasmic and absent nuclear immunoreactivity had a 6-fold increased risk of tumor-related death (P=0.005) compared to patients with strong expression. Considering only patients with high grade G3 tumors, a 7.8-fold risk of tumor-associated death and a 3.6-fold risk of tumor progression were detected independently of the histologic tumor subtype or the chemotherapy regimen. In summary, a combination of weak cytoplasmic and absent nuclear expression of Piwil 2 is significantly associated with an increased risk of DSS and tumor progression. This implicates that Piwil 2 could be a valuable prognostic marker for high-risk BCa patients.