Molecular markers in bladder cancer: Novel research frontiers.

Bladder cancer (BC) is a heterogeneous disease encompassing distinct biologic features that lead to extremely different clinical behaviors. In the last 20 years, great efforts have been made to predict disease outcome and response to treatment by developing risk assessment calculators based on multiple standard clinical-pathological factors, as well as by testing several molecular markers. Unfortunately, risk assessment calculators alone fail to accurately assess a single patient's prognosis and response to different treatment options. Several molecular markers easily assessable by routine immunohistochemical techniques hold promise for becoming widely available and cost-effective tools for a more reliable risk assessment, but none have yet entered routine clinical practice. Current research is therefore moving towards (i) identifying novel molecular markers; (ii) testing old and new markers in homogeneous patients' populations receiving homogeneous treatments; (iii) generating a multimarker panel that could be easily, and thus routinely, used in clinical practice; (iv) developing novel risk assessment tools, possibly combining standard clinical-pathological factors with molecular markers. This review analyses the emerging body of literature concerning novel biomarkers, ranging from genetic changes to altered expression of a huge variety of molecules, potentially involved in BC outcome and response to treatment. Findings suggest that some of these indicators, such as serum circulating tumor cells and tissue mitochondrial DNA, seem to be easily assessable and provide reliable information. Other markers, such as the phosphoinositide-3-kinase (PI3K)/AKT (serine-threonine kinase)/mTOR (mammalian target of rapamycin) pathway and epigenetic changes in DNA methylation seem to not only have prognostic/predictive value but also, most importantly, represent valuable therapeutic targets. Finally, there is increasing evidence that the development of novel risk assessment tools combining standard clinical-pathological factors with molecular markers represents a major quest in managing this poorly predictable disease.

Predictive markers in bladder cancer: do we have molecular markers ready for clinical use?

Bladder cancer (BC) is a heterogeneous disease. Approximately 75% of patients present with non-muscle-invasive BC (NMIBC), which has a high recurrence rate and a low but unpredictable progression rate. Conversely, patients with muscle-invasive BC (MIBC) are at high risk for progression and cancer-specific mortality, but, again, disease behavior is unpredictable. To date, risk assessment for tumor recurrence and progression is based on clinico-pathological factors only. A risk assessment calculator that is based on several such parameters is available for NMIBC, but it has been reported to have potential flaws. In the last two decades, great effort has been made to evaluate the prognostic and predictive role of several molecular markers in MIBC and, even more so, in NMIBC, where the need for more precise risk stratification is urgently needed. This review addresses current evidence for the role of several molecular markers easily assessable by immunohistochemical techniques in prognosticating/predicting the outcome of NMIBC and MIBC. To date, because of divergent results among the many studies, no molecular marker has yet entered routine clinical practice; however, some of them (e.g., p53, pRb, p21, and survivin) have proved their predictive value in studies that included a homogeneous patient population on standardized treatment, and, therefore, are probably ready for clinical validation on a larger scale. Even more interesting is the possibility of constructing multimarker panels that could be used in routine clinical practice, as all these markers can easily be evaluated by immunohistochemistry on routine surgical pathology specimens. The molecular markers described herein hold promise for becoming widely available and cost-effective tools for reliable risk assessment, which would represent a great advancement in counseling patients, in selecting them for neoadjuvant and adjuvant treatments, and in determining their eligibility for clinical trials.