Dose fractionation schemes for palliative external beam radiotherapy on painful bone metastasis from breast cancer

ABSTRACT

Background: The efficacy of palliative external beam radiotherapy (PRT) for relief of metastatic bone pain had been well established, a single fraction is as effective as multiple fractions in relieving bone pain, but variation exist among the radiation oncologist in our environment on the ideal dose per fraction regimen. Methods: We retrospectively reviewed data from breast cancer patients treated with PRT using linear accelerator for metastatic bone pain in University College Hospital Ibadan between 2005 and 2009. The extracted information includes bio-data, presenting symptoms, metastatic sites, and bone pain assessment before and after four weeks of PRT using visual analogue pain scale (VAS), radiation doses, fractionation numbers and number of re-irradiation. Results: There were 161 eligible breast cancer patients who were treated with PRT secondary to painful bone metastases between 1st January 2005 and 31st December 2009. Majority were females with only 1.2% male patients (Figure 1). Table 1 showed demographic characteristics of treated patients with mean age of 45.2 years, pain was the major presenting complaint (92.5%) and multiple bony metastases constituted the highest metastatic presentation (52.2%). Table 2 shows patient's responses to PRT treatment for pain relief (complete responses of 88.8% and 11.2% partial responses). No significant association between patient's responses to PRT and magnitude of radiation doses delivered. However, fractionation sizes were significantly associated with re-irradiation p-value < 0.05. Conclusion: No differences exist between various dose fractionation schemes in terms of relief from painful bony metastases. However, shorter dose fractionation schemes are associated with re-irradiation of previously irradiated sites