Knowledge-Based Assessment of Focal Dose Escalation Treatment Plans in Prostate Cancer

Area of Science:

• Radiation Oncology
• Medical Physics
• Prostate Cancer Treatment

Background:

• The FLAME trial investigated focal dose escalation in prostate cancer radiation therapy.
• Organs at risk (OAR) dose constraints can limit tumor dose escalation, potentially leading to suboptimal planning.

Purpose of the Study:

• To assess the effectiveness of focal dose escalation in prostate cancer.
• To develop and validate an anatomy-based prediction model for identifying suboptimal tumor dose in radiation plans.
• To investigate the potential for replanning to improve tumor dose delivery.

Main Methods:

• Derived dose-volume parameters from 539 FLAME trial patients across four institutions.
• Developed a linear regression model using patient anatomy features to predict tumor D98% (dose to 98% of the tumor volume).
• Performed replanning on 21 selected plans to validate the prediction model's accuracy.

Main Results:

• In the dose-escalated arm, 99% of tumors received a dose greater than 107% of the standard dose (82.4 Gy).
• Anatomy-based prediction model identified features predictive of tumor D98%, with a median predicted increase of 4.4 Gy.
• Replanning increased median tumor D98% by 3.0 Gy, showing strong correlation (ρ = 0.86) with predicted increases.

Conclusions:

• Focal dose escalation to the prostate tumor is achievable and feasible.
• The developed prediction model effectively identifies plans where higher boost doses can be delivered.
• The model shows promise as a quality assessment tool for focal dose-escalated radiation therapy plans.