Five Fraction External Beam Partial Breast Irradiation: A User's Guide

Area of Science:

• Radiation Oncology
• Breast Cancer Treatment
• Evidence-Based Medicine

Background:

• Mature follow-up from randomized trials confirms the safety and efficacy of external beam partial breast irradiation (PBI) for selected early-stage breast cancer patients.
• Despite robust evidence, external beam PBI is currently underutilized in clinical practice.
• This highlights a need for practical guidance to facilitate wider adoption.

Purpose of the Study:

• To provide a user guide for implementing evidence-based external beam partial breast irradiation (PBI).
• To outline optimal patient selection criteria for PBI.
• To detail the recommended workflow and address potential challenges in PBI delivery.

Main Methods:

• Review of current guidelines for PBI suitability and patient selection.
• Discussion of surgical considerations, including optimal timing post-surgery (3-5 weeks).
• Detailed description of treatment technique, simulation, contouring, and planning, including target volume expansions (0.5-1.0 cm) and organ-at-risk dose constraints.

Main Results:

• Prospective data supports a regimen of 30 Gy in 5 fractions using intensity-modulated radiation therapy (IMRT) for PBI.
• Achievable organ-at-risk dose constraints include heart V3Gy ≤10% and contralateral breast Dmax ≤1 Gy.
• Specific recommendations for clinical target volume and planning target volume expansions are provided.

Conclusions:

• Five-fraction external beam PBI is a highly effective treatment with minimal toxicity for early-stage breast cancer patients post-breast-conserving surgery.
• Intensity-modulated radiation therapy (IMRT) techniques allow for significant normal tissue sparing.
• Feasibility of implementation is high at most radiation oncology centers due to standard linear accelerator use.