Comparing Interfractional Stability of Heart Dose Among Three Breath-Hold Radiotherapy Techniques in Breast Cancer

Area of Science:

• Radiotherapy
• Medical Physics
• Oncology

Background:

• Breath-holding techniques are crucial for reducing cardiac dose in left-sided breast cancer radiotherapy.
• Reproducibility of mean heart dose (MHD) is essential for effective treatment and minimizing cardiac toxicity.

Purpose of the Study:

• To compare the reproducibility of MHD among three common breath-hold techniques: voluntary deep inspiration breath hold (vDIBH), active breathing control (ABC), and surface-guided radiotherapy (SGRT).
• To determine if any technique offers superior MHD reproducibility during radiotherapy for left-sided breast cancer.

Main Methods:

• A prospective, three-armed trial involving 55 patients undergoing radiotherapy for left-sided breast cancer.
• MHD was assessed using planning CT and weekly cone-beam CT (CBCT) scans.
• Interfractional variation of MHD and the difference between cumulative MHD at CBCT and planning CT were calculated and compared across vDIBH, ABC, and SGRT groups.

Main Results:

• Surface-guided radiotherapy (SGRT) demonstrated a slightly greater interfractional variation in MHD compared to vDIBH and ABC (P=0.0052 and P=0.026, respectively).
• The cumulative MHD at CBCT was lower than at planning CT in the SGRT group (mean difference: -22.1 cGy, P=0.013), but not in vDIBH or ABC groups.
• No significant differences were observed in the reproducibility of cumulative MHD at CBCT relative to planning CT among the three techniques (all P > 0.1).

Conclusions:

• While SGRT showed a trend towards greater interfractional MHD variation, the difference may not be clinically significant.
• All three breath-hold techniques (vDIBH, ABC, SGRT) demonstrated comparable reproducibility of MHD at CBCT in relation to planning CT.
• These findings suggest that vDIBH, ABC, and SGRT are broadly effective in maintaining reproducible cardiac doses during radiotherapy.