Short- and long-term effects of 1⁸⁶Re-1,1-hydroxyethylidene diphosphonate in the treatment of painful bone metastases

This study evaluates the short- and long-term therapeutic efficacy of ¹⁸⁶Re-1,1-hydroxyethylidene diphosphonate (HEDP) in the palliation of painful bone metastases and the influence of variables before therapy in determining the characteristics of pain palliation. Methods: Sixty patients with painful bone metastases from different tumor types were treated with 1406 MBq ¹⁸⁶Re-HEDP. After treatment, the patients were followed up clinically at weekly intervals for the first month and monthly thereafter up to 1 y, until death or pain relapse. Pain response was graded as complete, partial, minimal, or absent using the Wisconsin test scoring system. Duration of pain relief, performance status, tumor markers, serum alkaline phosphatase levels, hematologic toxicity, and metastatic bone progression were also evaluated. Results: Overall, 80% of individuals experienced prompt relief of pain, with 31% complete, 34% partial, and 15% minimal responses. Transient World Health Organization grade 1-2 hematologic toxicity was apparent, with a decrease in the mean platelet (32%) and mean leukocyte (18%) counts at 3 and 4 wk, respectively. The degree of pain response did not correlate with any pretreatment variable. The duration of pain relief ranged from 3 wk to 12 mo and correlated positively with the degree of response (P = 0.02) and negatively with pretreatment scintigraphic scores and alkaline phosphatase levels (P = 0.02). Conclusion: ¹⁸⁶Re-HEDP is effective for fast palliation of painful bone metastases from various tumors. The effect tends to last longer if patients are treated early in the course of their disease.