Impact of zoledronic acid (Z) on pain in prostate cancer patients with bone metastases in a randomised placebo-control trial

Abstract

4638 Background: Bone metastases occur in up to 80% of advanced prostate cancer patients and can results in painful Skeletal-Related Events (SREs). Z is the only biphosphonate approved for metastatic prostate cancer that decreases the occurrence of SREs which include pathologic fractures, severe bone pain requiring radiation therapy, spinal cord compression, surgery to bone and hypercalcemia of malignancy which may lead to daily activity limitations. We performed retrospective analyses on data from a placebo-controlled study of Z to investigate which items of the Brief Pain Inventory (BPI) were most sensitive to changes in patient’s pain due to treatment. Methods: Prostate cancer patients with bone metastases received Zoledronate 4 mg (n = 201) or placebo (n = 201). The BPI was administered at baseline (visit 2), and visits 3 (weeks 3–4), 4 (weeks 6–8), and then every second visit (every 6 weeks) until study end. Changes in BPI individual item scores and the Pain Severity and Pain Interference scale scores were compared between Z and placebo groups. Post-baseline missing data was replaced by Last Observation Carried Forward (LOCF). Results: Z was statistically significantly better than placebo for changes in BPI items ‘pain at its worst’, ‘pain at its least’, ‘pain on average’, and the BPI pain severity scale (p < 0.05) at visit 4 (weeks 6–8), and visit 6 (week 12). For ‘pain right now’ there were statistically significant differences at visit 4, but not visit 6. Z was also superior to placebo for ‘pain right now’ and the Pain Severity and Interference scales at visit 12 (week 30–32) (p < 0.05). Finally Z was superior to placebo for ‘interference with general activities’ at visits 12 (week 30–32), 16 (weeks 42–44), and LOCF (p < 0.05). Conclusion: Our findings suggest that Z significantly reduces bone pain and general activity limitations in prostate cancer patients with bone metastases. Several items in the BPI are more sensitive to Z treatment including ‘pain at its worst’, ‘pain at its least’, ‘pain on average’, and the BPI Pain Severity scale. [Table: see text]