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

## TL;DR

This study finds that prostate cancer with limited bone metastases and lung metastases may have a better prognosis than previously thought.

## Contribution

The study identifies that lung metastases do not worsen prognosis when coexisting with limited bone metastases in prostate cancer.

## Key findings

- Higher volume of bone metastases correlates with worse survival outcomes.
- Lung metastases do not negatively impact prognosis when coexisting with bone metastases.
- Lung metastases show lower progression to castration-resistant prostate cancer compared to bone metastases.

## Abstract

In this study, we conducted a retrospective assessment of the metastatic patterns associated with a favorable prognosis in metastatic castration-sensitive prostate cancer with bone metastasis, including the coexistence of lung metastasis. Our multivariate analyses of overall survival and castration resistance-free survival revealed that prognoses worsened as the extent of bone metastases increased. However, the coexistence of lung and bone metastases had no prognostic impact. We conclude that prostate cancer with fewer bone metastases, even with lung metastasis, should be viewed differently from the prevalent notion that metastatic prostate cancer generally has an unfavorable prognosis.

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.