Strontium(89) chloride versus palliative local field radiotherapy in patients with hormonal escaped prostate cancer: a phase III study of the European Organisation for Research and Treatment of Cancer, Genitourinary Group.

Objectives: To compare toxicity, subjective response rate, time to subjective progression and overall survival in patients with painful bone metastases of hormone-resistant prostate cancer (HRPC) treated with a single intravenous injection of 150MBq (4mCi) Strontium(89) Chloride (S) or palliative local field radiotherapy (R) with the usual radiotherapy regimen used at each centre. The costs of both treatments were also assessed.

Patients And Methods: 101 patients were randomized to S and 102 to R. Time to event endpoints were compared with the Logrank test and Kaplan-Meier curves, in the intent-to-treat population (2-sided alpha=0.05).

Results: Baseline characteristics of both groups were comparable. There was a borderline statistically significant difference in overall survival in favour of the local field radiotherapy (R: 11 months; S: 7.2 months; p=0.0457). There was no difference in progression-free survival or time to progression. Subjective response was seen in 34.7% in the S-arm and in 33.3% in the R-arm. A biochemical response was observed in 10% and 13% of the R- and S-groups, respectively. There was no difference in treatment toxicity between the two groups.

Conclusion: In symptomatic HRPC, pain treatment with local field radiotherapy is associated with a better overall survival compared to Strontium(89). The lower costs of local field radiotherapy also favour the use of this treatment in patients with HRPC. The reason for the apparent survival benefit of localised radiation treatment is not clear.