Response evaluation of bone metastasis in prostate cancer: Preliminary comparison of computerized bone scan index versus standardized clinical criteria

The correlation between the computer-assisted bone scan index (BSI) responses versus clinical response classification if bone metastases in prostate cancer patients are not clear. We compared changes in BSI with Prostate Cancer Working Group-3 (PCWG3) and MD Anderson (MDA) criteria. Fifty-six consecutive patients with at least two bone scans (BS) within 12 months were included, who had BS before and after treatment with the same anticancer agent. Progressive disease (PD) by PCWG3 criteria was seen in 28% of the cases (median BSI increased by 1.69 units) versus non-PD in 72% (BSI change -0.13). MDAnderson showed PD in 34% (BSI increase 0.49), 45% stable disease (BSI change 0.00), and 20% partial responses (BSI decrease 1.44). Absolute BSI changes differed significantly among response categories by PCWG3 and MDA criteria (both P0/≤0 and >0.3/≤0.3 BSI units) showed a significant correlation with PCWG3 and MDA criteria (all P