The aims of radiation therapy (RT) are either curative or palliative. According to the American statistics, about 45% of all cancer patients received RT during their course of illness from diagnosis to death, among which 25-30% received RT for the purpose of symptomatic relief. Bone metastasis is one of the major causes of cancer pain, which has been known to be effectively alleviated by RT. Palliative RT for pain relief has been applied with various doses and treatment schedules, from single fraction to multiple fractions over 2 weeks or longer.

Prospective randomized clinical trials have been performed since late 90's to compare palliative effects and adverse side effects by single fraction and multiple fractions in the palliative RT for bone metastasis, which showed that the single fraction had the equivalent palliative results when compared to multiple fractions. In particular, it is found in the literatures that the single fraction can be preferred in patients with short life expectancy of less than a few months. On the other hand, schedules of multiple fractions are preferred even in patients with bad prognosis, supported by the argument that the previous studies are not reliable because of high drop-out rates in the analysis.

Since no systematic studies on standard RT for patients with bone metastasis have been performed in Korea, the necessity has arisen for a study on the optimal palliative RT schedule in patients with short life expectancy, fully considering the adequacy of treatment effect, the accessibility to treatment, and the expenses. Therefore, this study was intended to find the evidence and the differences in the patterns of RT practice in patients with bone metastasis in Korea, and to find the clues to overcome those differences.