Re-irradiation for painful bone metastases: evidence-based approach

The prognosis of patients with bone metastases has improved with the advent of increasingly effective systemic treatment and better supportive care. A growing number of bone metastases patients now outlive the duration of benefits from their initial treatment of radiotherapy (RT) while some patients fail to initially respond to RT. As such, re-irradiation (re-RT) may be required. The current review updates the literature on findings in the area of re-RT. In particular, the recent publication of the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) Symptom Control (SC20) trial shows that an 8 Gy treatment in a single fraction for re-RT is non-inferior and less toxic than 20 Gy in multiple fractions. Furthermore, patients responding to re-RT have experienced superior quality of life (QoL) and complain of less functional interference from pain; this provides a strong case in support of bone metastases patients being offered re-treatment. However, despite such findings, some specific patients will never respond to initial radiation or re-RT. New evidence suggests significant differences in bone markers between responders and non-responders, thus opening the possibility for further research into the use of such biomarkers for predicting prognosis and for the guidance of consequent treatment decisions.