Prognostic Value of Bone Metastases by Extent of Disease and Lung Metastases in High-Volume Castration-Sensitive Prostate Cancer: A Retrospective Study

Backgrounds: High-volume (HV) metastatic castration-sensitive prostate cancer (mCSPC) is an aggressive disease. Despite this, we aimed to assess the metastatic patterns associated with a favorable prognosis in HV disease with bone metastasis (BM), including BM’s coexistence with lung metastasis (LM). Methods: We retrospectively analyzed 379 patients with synchronous mCSPC. They were categorized using the CHAARTED criteria as low-volume (LV) or HV with BM, classified based on extent of the disease from 1 to 4 (HV-EOD1–4) with or without LM. Multivariate Cox models for overall survival and castration-resistance-free survival assessed the prognostic values of HV-EOD1–4 compared with LV disease and the presence of LM. Site-specific radiographic progression at the time of castration-resistant prostate diagnosis was assessed in patients with BM and LM. Results: Multivariate analyses for overall survival showed no prognostic value of HV-EOD1 (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.43–1.85; p = 0.77), HV-EOD2 (HR 1.17; 95% CI 0.69–1.99; p = 0.57), and LM (HR 1.29; 95% CI 0.80–2.07; p = 0.29). In the analyses, HV-EOD ≤ 2 and LM did not influence castration resistance-free survival. LM showed a significantly lower incidence of radiographic progression to castration-resistant prostate cancer than BM (6.0% vs. 29.9%, p < 0.001). Conclusions: This study indicates the prognostic heterogeneity of HV disease considering BM and LM. These findings may aid in determining the treatment intensity for mCSPC.