The role of biomarkers in bladder preservation management of muscle-invasive bladder cancer.

Patients with localized muscle-invasive bladder cancer (MIBC) can choose to undergo either neoadjuvant chemotherapy followed by radical cystectomy or radiation therapy-based bladder preservation treatment modality with subsequent close cystoscopic surveillance with salvage cystectomy reserved for patients with evidence of local disease recurrence. At the present time, the decision regarding bladder-directed local therapy for MIBC is based on physicians' and patients' preferences, and does not take into account tumor biology. Predictive biomarkers, once validated, could offer a more patient-centered and biology-driven selection of bladder-directed therapies. We provide a narrative review of clinical data pertaining to the biomarkers in bladder preservation management of MIBC. There are currently no validated and clinically used biological markers used for stratification of radical bladder treatment and selection of bladder-preserving therapies. This article summarizes biomarkers that could have a potential clinical utility-PD-L1, molecular subtypes, Ki-67, MRE-11 and markers of hypoxia-and offers a hypothetical pathway model for a marker-driven precision management of medically operable patients with a newly diagnosed MIBC. When selecting the optimal cancer treatment, both patient and tumor factors need to be considered. Once validated, biological markers will help clinicians tailor the management of MIBC to individual patients.