Stereotactic body radiotherapy for bone-only oligometastatic bladder Cancer: a multi-institutional experience

Area of Science:

• Oncology
• Radiation Oncology
• Urologic Oncology

Background:

• Bladder cancer with limited bone metastases (oligometastatic) presents unique treatment challenges.
• Stereotactic body radiotherapy (SBRT) is an emerging option for localized bone metastases.
• Understanding SBRT's efficacy and failure patterns in bone-only oligometastatic bladder cancer is crucial.

Purpose of the Study:

• To evaluate clinical outcomes, failure patterns, local control (LC), and time to next systemic therapy (TTNT) after SBRT.
• To assess SBRT's role in patients with bone-only oligometastatic bladder cancer.

Main Methods:

• Retrospective analysis of 26 patients with bone-only oligometastatic bladder cancer treated with SBRT.
• Patients received metastasis-directed SBRT to ≤3 bone lesions across four institutions (2012-2020).
• Kaplan-Meier method used to estimate overall survival (OS), progression-free survival (PFS), TTNT, and LC.

Main Results:

• Excellent 1- and 2-year local control rates of 94.7% and 88.0%, respectively, with no grade ≥3 toxicities.
• Median OS was 8.9 months; median PFS was 5.8 months.
• Systemic progression was common (46.2%), predominantly distant metastasis; median TTNT was 4.4 months.

Conclusions:

• SBRT demonstrates excellent local control and minimal toxicity for bone-only oligometastatic bladder cancer.
• Systemic disease progression remains a significant challenge, limiting overall survival benefits.
• Prospective studies are warranted to define SBRT's optimal role within multimodal treatment strategies.