Proton versus photon comprehensive nodal breast irradiation

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Traditional 3DCRT planning for comprehensive nodal breast irradiation uses a three or four field photon technique.
• This technique can lead to concerning ipsilateral lung and heart doses, depending on patient anatomy.
• Established dose constraints aim to limit lung V20 to <35% and heart mean dose to <3Gy.

Observation:

• Double scattering proton therapy utilizes the Spread-Out Bragg Peak for precise dose delivery and rapid fall-off.
• This inherent characteristic of proton therapy offers a potential advantage in minimizing dose to organs at risk.
• The study compared dose metrics between photon and proton therapy for comprehensive nodal breast irradiation.

Findings:

• Proton therapy demonstrated a significant reduction in ipsilateral lung V20 across all evaluated plans.
• The mean heart dose was decreased in most patients treated with proton therapy.
• One patient experienced an increased heart mean dose with proton therapy, attributed to unique anatomical factors.

Implications:

• Proton therapy is a beneficial alternative for comprehensive nodal breast irradiation, particularly when photon plans exceed dose constraints.
• It is also advantageous in re-irradiation scenarios for breast cancer.
• This modality enhances patient safety by reducing radiation exposure to critical organs like the lungs and heart.