Strontium-89 for symptomatic metastatic prostate cancer to bone: recommendations for hospice patients

In our institution, 4 mCi doses of the radiopharmaceutical strontium-89 (Sr89) have been given to 101 prostate cancer patients suffering from symptomatic bone metastases. Patients were prospectively analyzed for pain response, treatment-related hematologic toxicity, and survival. Pre-treatment clinical factors were correlated with outcome. Karnofsky Performance Scores (KPS) predicted for survival and pain response. Myelosuppression from the Sr89 treatment was minimal. Twenty-eight of the treated patients had a KPS of 60 or less. This group of patients had a median actuarial survival of 17.5 weeks, and collectively, met Hospice admission survival criteria. In a subset analysis of this group, patients with a KPS of 50 or less demonstrated a low pain response (40%) and average survival (12.5 weeks), both of which did not appear to justify the significant cost and risk of toxicity associated with Sr89 treatment. In these patients, opioids appeared to offer more cost-effective pain control. Patients with a pre-treatment KPS score of 60 had a mean survival of 20.5 weeks following Sr89 therapy, with 42 percent of patients experiencing a reduction in pain. We conclude that patients with a pretreatment KPS of 50 or less should not be treated with Sr89 and patients with a pretreatment KPS of 60 should be evaluated on a case-by-case basis to determine whether or not Sr89 represents the most reasonable treatment option for palliation of their bone pain.