Will the Use of Biomarkers Improve Bladder Cancer Radiotherapy Delivery?

Advances in the field of cancer biology and molecular techniques have led to a better understanding of the molecular underpinnings driving cancer development and outcomes. Simultaneously, advances in imaging have allowed for improved sensitivity in initial staging, radiotherapy planning and follow-up of numerous cancers. These two phenomena have led to the development of biomarkers that can guide therapy in multiple malignancies. In bladder cancer, there is extensive ongoing research into the identification of biomarkers that can help tailor personalised approaches for treatment based on the intrinsic tumour biology. However, the delivery of bladder cancer radiotherapy as part of trimodality therapy currently has a paucity of biomarkers to guide treatment. Here we summarise the existing literature and ongoing investigations into potential predictive and prognostic molecular and imaging biomarkers that may one day guide selection for utilisation of radiotherapy as part of trimodality therapy, guide selection of the radiosensitising agent, guide radiation dose and target, and guide surveillance for recurrence after trimodality therapy. •Historically, there have been no validated biomarkers to guide the use of radiotherapy as part of trimodality therapy (TMT) for bladder cancer.•Emerging data suggest several candidate predictive and prognostic molecular biomarkers, such as MRE11, DNA damage response (DDR) mutations and gene expression profiles, that may help to identify patients who are optimal candidates for radiotherapy as part of TMT.•Ongoing investigations are studying biomarkers such as the radiation sensitivity index, which may help to guide the optimal radiation dose to maximise the therapeutic ratio.•The 24-gene hypoxia signature, DDR mutations and markers of immune activation are potential biomarkers that may help to guide the use of radiosensitising systemic therapy and immunotherapy and are undergoing active investigation.•Liquid, tumour and imaging biomarkers are being studied to determine if they can improve upon initial staging and surveillance for recurrence after TMT.