Multicentre trial on the efficacy and toxicity of single-dose samarium-153-ethylene diamine tetramethylene phosphonate as a palliative treatment for painful skeletal metastases in China

A multicentre trial was organized in China as part of an international coordinated research project to study the efficacy and toxicity of single-dose samarium-153 ethylene diamine tetramethylene phosphonate (EDTMP) as a palliative treatment for painful skeletal metastases. One hundred and five patients with painful bone metastases from various primaries were treated with Sm-153-EDTMP at a dose of 37 MBq/kg(group I) or 18.5 MBq/kg (group II). The effects were evaluated according to change in daily analgesic consumption, pain score, sum of effect product (SEP), Physician's Global Assessment (PGA), blood counts, and organ function tests conducted regularly for 16 weeks. Fifty-eight of 70 patients in group I and 30 of 35 ingroup II had a positive response, with SEPs of 22.29 +/- 14.47 and 20.13 +/- 13.90 respectively. Of 72 patients who had been receiving analgesics, 63 reduced their consumption. PCA showed that the Karnofsky score (KS) increased from 58.54 +/- 25.90 to 71.67 +/- 26.53, indicating improved general condition, but the difference was not significant. Among subgroups of patients, only those with breast cancer showed a significant change in the Karnofsky score after treatment. Inter-group differences were found for net change in KS between patients with lung and patients with breast cancer, and between patients with lung and patients with oesophageal cancer. Seventeen patients showed no response. No serious side-effects were noted, except for falls in the white blood cell (nadir 1.5 x 10(9)/l) and platelet (nadir 6.0 x 10(10)/l) counts in 44/105 and 34/105 cases, respectively. Ten patients had an abnormal liver function test. Response and side-effects were both independent of dose. In conclusion. Sm-153-EDTMP provided effective palliation in 83.8% of patients with painful bone metastases; the major toxicity was temporary myelosuppression. Further studies are needed to identify better ways of determining the appropriate dose in the individual case and the efficacy of treatment.