Dosimetric Comparison of Particle Radiotherapy and Photon VMAT for Left-Sided Breast Cancer Post Breast-Conserving...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Carbon ion radiotherapy shows promise for left-sided breast cancer treatment.
• Limited comparative dosimetric data exists between carbon ion, proton, and photon-based radiotherapy techniques.
• Evaluating heavy ion radiotherapy's potential is crucial for advancing breast cancer treatment.

Purpose of the Study:

• To retrospectively compare the dosimetric characteristics of carbon ion radiotherapy, proton radiotherapy, conformal radiation therapy (CRT), intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT).
• To assess treatment planning conformity and organ-at-risk (OAR) protection for left-sided breast cancer patients.
• To explore the potential benefits of heavy ion radiotherapy in this patient population.

Main Methods:

• Eighteen patients with stage I/II left-sided breast cancer after breast-conserving surgery were included.
• Treatment plans were generated using dedicated systems for photon beams, proton, and carbon ion therapy.
• Dosimetric parameters, including conformity index (CI) and homogeneity index (HI), were compared using the Friedman M-test.

Main Results:

• All treatment modalities achieved target coverage objectives.
• Carbon ion therapy demonstrated superior conformity compared to IMRT and CRT (P < 0.01), with no significant difference versus VMAT.
• Carbon ion therapy provided significant dosimetric advantages in protecting organs at risk, including the contralateral breast, heart, and contralateral lung, and showed superiority over proton therapy for ipsilateral lung V5 (P = 0.011).

Conclusions:

• Heavy ion therapies, particularly carbon ion, offer dosimetric advantages over photon and proton therapies in terms of planning conformity and OAR protection for left-sided breast cancer.
• These dosimetric benefits suggest potential for improved clinical outcomes and reduced treatment-related side effects.
• Further clinical investigation is warranted to confirm the therapeutic advantages of carbon ion radiotherapy.