The role of external beam radiotherapy in the management of bone metastases

Samarium lexidronam (153Sm-EDTMP): skeletal radiation for osteoblastic bone metastases and osteosarcoma

Radiation therapy can be an effective means to treat bone metastases, which occur in more than 50% of cancer patients. (153)Samarium lexidronam ((153)Sm-EDTMP; Quadramet, Cytogen) is a radiopharmaceutical designed for deposition into bone metastases. Bone scans can identify patients that may benefit from targeted radiation therapy with (153)Sm-EDTMP. As an unsealed source of radiation therapy, (153)Sm-EDTMP is simple to administer: 1 mCi/kg is given in a similar fashion to a bone scan injection ((99m)Tc-MDP bone scan injection is given at 0.2-0.35 mCi/kg. Therefore, both are administered intravenously. However, the radiation-absorbed dose and radiopharmaceutical energy are different). Nevertheless, despite simplicity of administration, (153)Sm-EDTMP is underutilized for improving cancer pain in the skeleton. Repeated cycles and combined treatment with other modalities such as bisphosphonates, chemotherapy and/or external beam radiation are possible. (153)Sm-EDTMP combined with bisphosphonates, chemotherapy and/or radiation may provide better palliation of bone metastases and also in bone-forming tumors (osteosarcoma). Encouraging experience using high-dose (153)Sm-EDTMP for total marrow irradiation in hematologic malignancies involving the bones (e.g., myeloma or acute leukemia) is also reviewed.

Management of painful bone metastases

PURPOSE OF REVIEW

This review examines recent data on the pathophysiology and mechanisms of bone pain; it highlights the use of multiple and interdisciplinary treatments rather than sole use of traditional analgesics.

RECENT FINDINGS

Bone pain has been shown to have a unique pathophysiology. Recent experimental (animal) models have revealed that, parallel to increased bone destruction, ipsilateral spinal cord segments that receive primary input from the cancerous femur exhibit several notable neurochemical changes. These mandate the use of opioid doses sufficient to inhibit the observed nociceptive behaviours; these doses are greater than those required to alleviate pain behaviours of comparable magnitude generated by inflammatory pain. Several substances have been tested in this animal model.

SUMMARY

According to new preclinical data, treatment of bone cancer pain requires multidisciplinary therapies such as radiotherapy applied to the painful area along with systemic treatment (hormone therapy or chemotherapy) and supportive care (analgesic therapy and bisphosphonates). In some selected cases use of radioisotopes and other noninvasive or minimally invasive techniques may be useful in the management of metastatic bone pain. The treatment should be individualized according to the patient's clinical condition, life expectancy, and quality of life.