Introduction of a new semi-quantitative index with predictive implications in patients with painful osseous metastases after (186)Re-HEDP therapy.

AIM: In this study, a new method has been used to predict pain response to (186)Re-HEDP therapy in patients suffering from painful osseous metastases, on the basis of a modified bone scan index and pre-therapy pain scoring. METHODS: Forty five patients received a total of 73 doses of (186)Re-HEDP during a period of pain relapse without extra-osseous disease progression. All patients were under stable regimen of zoledronic acid, far off other therapeutic manipulations. Imaging studies regarding a modified estimation of bone scan index, were applied; the value of the largest bony lesion (called mBSI), provided that it also corresponded to the most prominent site of osseous pain was taken into account, and a new semi-quantitative index called Double Product Value (DPV), equal to pre-therapy pain score times mBSI was entered in the result analyses, to investigate any possible correlations with response endpoints. RESULTS: Favourable response occurred in 35/47 evaluated therapeutic doses of (186)Re-HEDP (74.5%; excellent response in 12 doses, 25.5%). Responders had significantly lower DPV (3.4 ± 2.3 vs. 10.2 ± 6.2, P=0.0029, for non-responders). Patients with pre-therapy DPV 4, and also a longer median period of pain relief (respective mean values 5.9 versus 2.1 months, HR 2.82; P=0.0001). CONCLUSION: DPV, as developed and implemented in this study proved a valuable and reproducible pre-therapy tool for assessing degree and duration of pain response after (186)Re-HEDP therapy.