Fractionating Boost Dose in Postoperative Breast Radiotherapy

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Mild hypofractionation is the preferred method for postoperative breast radiotherapy.
• A radiation boost after whole-breast irradiation can further reduce local recurrence risk in specific patient groups.
• Optimal dose and fractionation for radiation boosts remain under clinical discussion.

Purpose of the Study:

• To calculate the biologically effective doses (BEDs) of whole-breast irradiation (WBI) and boost radiotherapy (RT) from prominent clinical trials.
• To propose evidence-based dose and fractionation guidelines for postoperative breast radiation boosts.
• To evaluate the efficacy and potential drawbacks of longer boost RT schedules.

Main Methods:

• Utilized the linear-quadratic model to compute BED values for WBI and boost RT.
• Analyzed data from highly cited clinical trials on postoperative breast radiotherapy.
• Compared BED values across different fractionation schemes for boost RT.

Main Results:

• Whole-breast irradiation requires a BED of 65-75 Gy3.5.
• A boost BED of 15-19 Gy3.5 is deemed sufficient for reducing local recurrence.
• Boost RT schedules exceeding 20 Gy3.5 BED show no additional benefit and may increase risks.

Conclusions:

• Established trial-based BED ranges for effective postoperative breast radiotherapy.
• Recommended a specific BED range for radiation boosts to balance efficacy and toxicity.
• Advised against prolonged boost RT schedules due to lack of added benefit and potential harm.