Focal Boost to the Intraprostatic Tumor in External Beam Radiotherapy for Patients With Localized Prostate Cancer:...

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Prostate cancer (PCa) management often involves external beam radiotherapy (EBRT).
• Optimizing radiotherapy delivery to target intraprostatic tumor lesions is an area of active research.
• The FLAME trial previously suggested improved outcomes with focal boosting.

Purpose of the Study:

• To report 10-year outcomes of the FLAME trial, evaluating focal boosting in addition to standard EBRT for intermediate- and high-risk prostate cancer.
• To assess the long-term impact of focal boosting on biochemical disease-free survival (bDFS) and other survival endpoints.
• To explore dose-response relationships for focal boosting in prostate cancer radiotherapy.

Main Methods:

• A multicenter, randomized phase III trial comparing standard EBRT (77 Gy) with focal boost EBRT (up to 95 Gy) to MRI-visible lesions.
• 571 patients with intermediate- and high-risk PCa were randomized between 2009 and 2015.
• Long-term follow-up assessed bDFS, DFS, local DFS, regional lymph node DFS, DMFS, and OS, with dose-response analysis.

Main Results:

• The 10-year bDFS was significantly higher in the focal boost arm (86%) compared to the standard arm (71%).
• Significant improvements were observed for DFS, local DFS, and regional lymph node DFS, but not DMFS or OS.
• A dose-response relationship suggested an association between higher focal dose and reduced distant metastatic failure.

Conclusions:

• Focal boosting of intraprostatic lesions in addition to standard EBRT demonstrates a sustained 10-year benefit for bDFS in prostate cancer.
• This approach effectively prevents biochemical recurrence, potentially sparing patients the burden of cancer progression.
• While not impacting overall survival in this cohort, focal boosting shows promise for improving locoregional control and disease-free survival.