Radiotherapy for the palliation of painful bone metastases

Radiotherapy is used commonly to provide pain relief for painful bone metastases, and there is a perception that of the three-quarters of patients who achieve pain relief, half of these stay free from pain. However, the precise contribution from radiotherapy may be unclear because of difficulties in assessing the numbers of people achieving relief, the extent of relief and its duration, and the influence of other contemporaneous interventions, such as analgesics.

To assess pain relief from: 1. localised bone metastases achieved by radiotherapy, comparing the efficacy of different fractionation schedules 2. more generalised metastatic disease achieved by radiotherapy or radioisotopes.

Studies were identified by searching Medline (1966 to August 1998), Embase (1980 to 1998), the Cochrane Library (1998 Issue 3) and the Oxford Pain Relief Database (1950 to 1994).

The inclusion criteria used were: full journal publication, patients with pain due to bone metastases, and random allocation to a radiotherapeutic intervention (either external irradiation or administration of radioisotopes).

The number of patients achieving complete pain relief and at least 50% at one month were compared with an assumed natural history of 1 in 100 patients achieving pain relief without treatment to obtain the number-needed-to-treat (NNT). Summed pain relief or pain intensity difference over four to six hours was extracted, converted into dichotomous information yielding the number of patients with at least 50% pain relief, and used to calculate the relative benefit and the NNT for one patient to achieve at least 50% pain relief.

Twenty trials reported on 43 different radiotherapy fractionation schedules and eight studies of radioisotopes. Radiotherapy produced complete pain relief at one month in 395/1580 (25%) patients, and at least 50% relief in 788/1933 (41%) patients at some time during the trials. There were no differences in the proportions of patients achieving these outcomes between single or multiple fraction schedules. The number-needed-to-treat (NNT) to achieve complete relief at one month (compared with an assumed natural history of 1 in 100 patients whose pain resolved without treatment) was 4.2 (95% CI 3.7-4.7). No pooled estimates of speed of onset of relief, or of its duration, could be obtained. In the largest trial (759 patients) 52% of those who had complete relief had achieved it within four weeks, and the median duration of complete relief was 12 weeks. For more generalised disease, radioisotopes produced similar analgesic results to external irradiation. Adverse effect reporting was poor. There were no obvious differences between the various fractionation schedules in the incidence of nausea and vomiting, diarrhoea or pathological fractures.

Radiotherapy is clearly effective at reducing pain from painful bone metastases. There was no evidence of any difference in efficacy between different fractionation schedules, nor indeed of a dose-response with total dose of radiation. For treatment of generalised bone pain both hemibody irradiation and radioisotopes can reduce the number of painful new sites.