Sr89

Sr-89 (strontium-89) is a radioactive isotope of strontium used as a radiopharmaceutical for palliation of bone pain associated with skeletal metastases. It decays by beta emission to stable yttrium-89 with a half-life of 50.5 days.

In the body, strontium behaves chemically like calcium and accumulates in bone, particularly in areas of high osteoblastic activity such as metastatic lesions. The localized beta radiation reduces pain by damaging nearby nerve endings and tumor cells, often after several weeks.

Administration: It is given by intravenous injection as strontium-89 chloride (brand Metastron in some jurisdictions). A single dose is typical; treatment may be repeated under certain protocols, balancing potential pain relief against cumulative radiation dose to the bone marrow.

Safety and monitoring: The principal toxicity is bone marrow suppression, which can lead to reduced blood cell counts. Hematologic testing before and after treatment is standard. It is contraindicated in pregnancy and breastfeeding and in patients with significant anemia or other marrow suppression; precautions to limit radiation exposure are advised for caregivers and the environment.

Efficacy and limitations: Sr-89 provides palliation for metastatic bone pain but does not treat the underlying cancer or cure metastases. It is one option among systemic radiopharmaceuticals for symptom relief; other treatments include external beam radiotherapy and newer agents.