Biomarkers in patients treated with BCG: an update

Bacillus Calmette-Guerin (BCG) instillations are the recommended treatment for non-muscle invasive bladder cancer but high recurrence and progression rates remain after treatment. Despite patients risk stratification, BCG effectiveness remains unpredictable. A close, invasive and expensive follow up is mandatory. To improve or even replace this heavy surveillance in this high risk population, validated biomarkers were developed.

To identify the useful tools for the urologist in monitoring bladder cancer patients, we reviewed the literature focusing on plasma and urinary biomarkers of BCG-therapy outcome. Articles dated from 1988 to 2013 including specific keywords (urinary bladder neoplasm, biological markers, intravesical administration, recurrence) were examined and relevant papers were selected.

Before treatment initiation, genetic polymorphisms of multiple agents (cytokines, matrix-metalloproteinases) were found to become very useful to tailor therapy and monitoring. Those biomarkers belong to personalized medicine which is a topic of great interest today, but still need to be validated in cohorts from different ethnicities. During instillations, cytokines (IL-2, IL-8, IL-6/IL-10) were reported to be reliable to determine treatment response and efficacy. Further studies are needed to confirm results and standardize thresholds. After treatment, UroVysion, the FDA-approved fluorescence in situ hybridization (FISH), appeared to be the most robust marker of all the clinical parameters reviewed; but is not yet validated for BCG-treated patients.

No recommendations for everyday practice can be established today, but a combination of several markers and clinicopathological characteristics may be the future. As bladder cancer diagnosis and management are evolving, practicing urologists should be aware of and utilize bladder cancer markers in clinical practice.