Palliative response measurement in a phase III study of patients with prostate cancer and painful bone metastases: Secondary analysis of NCIC-CTG PR6

Abstract

9636 Background: In hormone-refractory prostate cancer (HRPC), clinical benefit can be measured using a composite palliative endpoint including pain intensity and analgesic use. This analysis examines the relationship between different measures of analgesic use and their correlation with palliative response and pain intensity. Methods: A secondary analysis was performed of a double-blind, placebo controlled, phase III trial examining the palliative response to mitoxantrone and prednisone with or without IV clodronate (Ernst DS, Tannock IF, Winquist EW, et al: J Clin Oncol 21:3335–3342, 2003). Using a daily analgesic diary and a 6 point pain intensity scale, 209 patients with HRPC and pain due to bone metastases recorded pain and analgesic scores (AS) at baseline and at each treatment visit. Palliative response was defined as a reduction from baseline in the PPI to 0 or by 2 points, or a reduction by 50% in the average daily AS over 2 visits, without an increase in either measure. In this analysis we measured: correlation between average daily AS and AS in the 24 hours prior to systemic therapy (24 hour AS); relationship between AS and PPI per cycle, correlation between palliative response based on average daily AS versus the 24 hour AS. Results: There was a strong correlation between the average AS and the 24-hour AS (correlation coefficient 0.77, p < 0.0001). Patients with high PPI scores had a higher AS (p < 0.0001).The association persisted when adjusted for baseline factors correlated to PPI (p < 0.0001). The correlation between palliative response based on average daily AS and 24-hour AS showed very close agreement (Kappa 0.89, 95% CI 0.83 - 0.96). Conclusions: AS over a 24 hour period prior to treatment appeared to correlate with daily average AS in HRPC patients and appears to be useful as a measure to determine the palliative response to systemic cancer therapy. No significant financial relationships to disclose.