Predictive value of bone scan index using computer-aided diagnosis system for bone scans in patients receiving first-line hormone therapy for metastatic hormone-sensitive prostate cancer.

225 Background: Recently, the CHAARTED and STAMPEDE studies showed a survival benefit for docetaxel when started with androgen deprivation therapy (ADT) in men with newly diagnosed metastatic hormone-sensitive prostate cancer (mHSPC). While GETUG-AFU 15 failed to demonstrate a survival benefit of early chemotherapy. New biomarker for select the candidate for early chemotherapy in mHSPC is warranted. The objective of this study is to evaluate the bone scan index (BSI) using computer-aided diagnosis system for bone scans for predictive factor in patients receiving ADT as first-line hormone therapy for mHSPC. Methods: We identified consecutive 85 mHSPC patients treated with maximum androgen blockade (MAB) as first-line hormone therapy. We analyzed the correlations between progression-free survival (PFS) of MAB and clinicopathological characteristics, including patients’ age, initial PSA levels, Gleason scores, clinical TNM stage, hemoglobin (Hb), lactase dehydrogenase (LDH), c-reactive protein (CRP), and bone scan index (BSI). Statistical analyses were assessed using cox proportional hazards regression models. Results: The median patients’ age was 73 and the median follow-up duration was 11.3months. The median initial PSA value was 270 ng/ml. Median BSI was 2.7 % (range: 0.0-14.6). Clinical or PSA progression occurred in 55 (64.7%) patients. The median time to progression was 12.9 months. In multivariate analysis, three significant risk factors for PFS were identified; patients’ age ( > 73 years old vs ≤ 73; HR 0.53, p = 0.038), initial PSA levels ( > 270 ng/mL vs ≤ 270; HR 0.53, p = 0.038), and BSI ( > 2.7 vs ≤ 2.7; HR 3.0, p < 0.000). We stratified the patients into two cohorts with low risk (0-1 risk factor present) and high risk (2-3 risk factors present). We found a significant difference in PFS among risk groups (median PFS 15.3 months vs 8.5, p < 0.000). Conclusions: Patients’ age, initial PSA levels, and bone scan index were the significant predictive factors for MAB as first-line hormone therapy in patients with mHSPC. These findings might support the decision-making of induction of early chemotherapy for mHSPC.