Bone density as a marker for local response to radiotherapy of spinal bone metastases in women with breast cancer: a retrospective analysis

Abstract

BackgroundWe designed this study to quantify the effects of radiotherapy (RT) on bone density as a local response in spinal bone metastases of women with breast cancer and, secondly, to establish bone density as an accurate and reproducible marker for assessment of local response to RT in spinal bone metastases.MethodsWe retrospectively assessed 135 osteolytic spinal metastases in 115 women with metastatic breast cancer treated at our department between January 2000 and January 2012. Primary endpoint was to compare bone density in the bone metastases before, 3 months after and 6 months after RT. Bone density was measured in Hounsfield units (HU) in computed tomography scans. We calculated mean values in HU and the standard deviation (SD) as a measurement of bone density before, 3 months and 6 months after RT. T-test was used for statistical analysis of difference in bone density as well as for univariate analysis of prognostic factors for difference in bone density 3 and 6 months after RT.ResultsMean bone density was 194.8 HU ± SD 123.0 at baseline. Bone density increased significantly by a mean of 145.8 HU ± SD 139.4 after 3 months (p = .0001) and by 250.3 HU ± SD 147.1 after 6 months (p < .0001). Women receiving bisphosphonates showed a tendency towards higher increase in bone density in the metastases after 3 months (152.6 HU ± SD 141.9 vs. 76.0 HU ± SD 86.1; p = .069) and pathological fractures before RT were associated with a significantly higher increase in bone density after 3 months (202.3 HU ± SD 161.9 vs. 130.3 HU ± SD 129.2; p = .013). Concomitant chemotherapy (ChT) or endocrine therapy (ET), hormone receptor status, performance score, applied overall RT dose and prescription of a surgical corset did not correlate with a difference in bone density after RT.ConclusionsBone density measurement in HU is a practicable and reproducible method for assessment of local RT response in osteolytic metastases in breast cancer. Our analysis demonstrated an excellent local response within metastases after palliative RT.

Limited short-term effect of palliative radiation therapy on quantitative computed tomography-derived bone mineral density in femora with metastases

“…This may indicate that the effect in ROI-PF was mainly due to BMD changes in the lesions (ROI-ML) and suggests that the irradiated femoral bone inside the radiation field but outside the lesion is unaffected or less affected by RT. A few studies found a smaller BMD increase in irradiated normal-appearing bone surrounding lytic metastases in vertebrae compared with the regions with vertebral lesions 10, 11. However, to our knowledge, the effect of RT on total bone volume in the radiation field has not been studied previously.…”

“…Additionally, some studies report a beneficial effect of RT on bone mineral density (BMD),8, 9, 10, 11, 12 which is also the clinical experience of medical specialists. In contrast, this beneficial effect was not confirmed in a recent systematic review 13 .…”

“…Previous research suggested that 24 Gy in 4 fractions postponed pathological fractures when compared with a single dose of 8 Gy 17 . However, studies on the effect of RT doses on BMD are limited, and the reported responses differ between studies 8, 9, 10, 11, 12. To date, only Koswig et al compared SF and MF in terms of BMD and found a greater response after MF RT 8 …”

“…Most studies included an analysis of lytic lesions in the vertebrae8, 9, 10, 11 but the effect of RT on BMD in blastic or mixed lesions was often not considered. Although the femur is also frequently affected,18, 19 few studies analyzed the effect of RT on BMD in femoral lesions 8, 9, 12.…”

CT-Guided 125I Seed Interstitial Brachytherapy as a Salvage Treatment for Recurrent Spinal Metastases after External Beam Radiotherapy

“…Bone metastases are a growing problem among patients who are living longer, with the spine being the most commonly affected site [2, 3]. Although external beam radiotherapy (EBRT) has long been the main form of treatment for spinal metastases [4–7], local recurrence in previously irradiated spinal segments has been reported in more than one-third of long-term survivors with malignancy [8]. Since EBRT was failure for the first time, reirradiation of spinal metastases presents a particular therapeutic challenge in radiation oncology.…”