Radiotherapy for bone metastases: practice in Norway 1997-2007. A national registry-based study.

Numerous randomised clinical trials have shown that the efficacy of single fraction radiotherapy for metastatic bone pain corresponds to that of multiple fractions of radiotherapy for the majority of patients. It is not clear to which extent single fraction radiotherapy has been implemented into clinical practice.A Norwegian national registry-based study was conducted, including all radiotherapy schedules of 8 Gy × 1 and 3 Gy × 10 delivered to bone metastases in 1997-2007. Binomial regression analyses were used to study whether treatment centre, primary diagnosis, anatomical region irradiated, age, sex, and travel distance, were associated with the choice of fractionation.A total of 14 380 radiotherapy episodes were identified. During the period 31% of the treatments were delivered as 8 Gy × 1. The proportion of single fraction treatments increased from 16% in 1997 to 41% in 2007. There were substantial differences in the proportion of single fraction treatments between the treatment centres (range 25-54%). These differences persisted after adjustment for sex, age, primary diagnosis, anatomical region, and travel distance.The study demonstrates an underutilisation of single fraction treatment for bone metastases in Norway during the study period.