The remineralization of the vertebral metastases of breast carcinoma after radiotherapy

BACKGROUND: The early detection of effects caused by radiotherapy on bone mineralisation has influence on clinical treatment. Usually the follow-up is done by conventional X-rays, presenting a loss of calcification of at least 30%. Quantitative CT-measurements are much more sensitive. PATIENTS AND METHODS: In a prospective study we evaluated the CT-scans of 14 patients with multiple vertebral metastases of mamma carcinoma. Our patients underwent SEQCT (one 10 mm slice in each affected vertebral body, 80 kV, 250 mAs) before and immediately after radiation therapy (total dose 30 Gy to 36 Gy) followed by further examinations 6 weeks and 3 months later. RESULTS: While there is no significant change in increased BMD (bone mineral density) of osteosclerotic and decreased BMD of osteolytic metastases just after therapy, the following examinations present an increase of BMD in osteolytic metastases 6 weeks after therapy more distinct 3 months after. Osteosclerotic metastases show a decline in bone density. In mixed metastases is no significant change while normal bone lying in the irradiation field demineralizes. Additive chemotherapy is very important especially for mineralisation of lytic metastases. Referring to mixed metastasis in one vertebral body we suggest a separate evaluation of the left and right side. CONCLUSION: Mineralizing effects of radiation therapy depend on the characteristics of the metastases. Supported by QCT histopathological change can be documented and exactly demonstrated to the clinician.