Personalized radiation therapy and biomarker-driven treatment strategies: a systematic review

Radiosensitivity varies to a great extent across tumor types and also between patients bearing the same type of tumor. Radiation oncology pioneered the field of biomarkers with attempts to correlate tumor response to clonogenic survival, tumor potential doubling time (Tpot), and PaO₂. Biomarkers predicting the clinical outcome after radiotherapy are already available, but their levels of evidence are heterogeneous. In light of these molecular factors, the issue of personalized radiation therapy in combination or as a standalone modality is addressed. Known molecular prognostic and predictive biomarkers and their present or potential respective therapeutic implications are described for six tumor types where radiotherapy is considered to be part of the mainstay: chemoradiation (e.g., gliomas, head and neck, cervical cancer), radiotherapy with or without androgen deprivation (e.g., prostate), neo-adjuvant chemoradiation (e.g., rectum), or adjuvant radiotherapy (e.g., breast).