What are the benefits and risks of Deep Inspiration Breath Hold (DIBH) technique versus free breathing during radiotherapy for a patient with left-sided breast cancer?

Deep Inspiration Breath Hold (DIBH) Should Be Standard Practice for Left-Sided Breast Cancer Radiotherapy

DIBH is strongly recommended over free breathing for left-sided breast cancer radiotherapy, as it significantly reduces cardiac and lung radiation exposure, thereby decreasing long-term cardiovascular morbidity and mortality without compromising tumor coverage. 1

Benefits of DIBH Technique

Cardiac Dose Reduction

• DIBH reduces mean heart dose by 36-47% compared to free breathing, with the largest prospective study (585 patients) showing reduction from 2.2 Gy to 1.3 Gy 2, 3
• Left anterior descending coronary artery (LAD) dose is reduced by 35-78%, with mean doses dropping from 14.3-24.71 Gy with free breathing to 4.1-4.67 Gy with DIBH 2, 4, 3, 5
• Left ventricle mean dose decreases by approximately 46% (from 2.8 Gy to 1.5 Gy), with volumetric parameters (V10-V30 Gy) reduced by nearly 100% 3
• The European Society of Cardiology emphasizes this is critical because higher cardiac radiation doses directly increase risk of major coronary events beginning within 5 years and continuing for three decades 1

Lung Dose Reduction

• Mean ipsilateral lung dose is reduced by 12-16% with DIBH 2, 5
• Irradiated lung volumes decrease by at least 20% due to increased lung volume during inspiration and reduced lung density 5
• This reduction in lung exposure minimizes radiation pneumonitis risk while maintaining the recommended limit of 3-3.5 cm of lung tissue in the treatment field 6, 7

Cardiovascular Risk Reduction

• DIBH reduces cumulative 10-year cardiovascular disease risk by 5% (from 3.59% to 3.41%) in the largest prospective study 2
• Normal tissue complication probability (NTCP) for long-term cardiac mortality decreases by approximately 11% 5
• NTCP for pneumonitis is also reduced by about 11% with DIBH 5

Patient Selection and Feasibility

Who Benefits

• At least 75% of left-sided breast cancer patients achieve clinically relevant cardiac dose reduction with DIBH, making it appropriate as standard practice rather than selective use 1
• DIBH is particularly beneficial when free breathing plans show mean heart dose ≥2 Gy 8

Patient Requirements

• Patients must be able to hold breath for 20 seconds to be eligible for DIBH 2
• Approximately 14% of eligible patients do not tolerate DIBH during simulation and require free breathing technique 8
• Individual coaching and determination of breathing amplitude during planning CT improves success rates 3

Implementation Requirements

Technical Specifications

• CT-based treatment planning is mandatory to delineate cardiac structures and verify dose reduction 1
• Surface-guided systems (such as Catalyst or Active Breathing Coordinator) with audio-video feedback ensure stable and reproducible breath-holds 2, 8, 3
• Breath-hold stability is excellent: mean setup difference within single breath-hold is 0.4 mm, between different breath-holds 1.1 mm, and between different treatment days 2.6 mm 8

Standard Dosing Protocols

• Hypofractionated regimen: 40.05 Gy in 15 fractions 2
• Normofractionated regimen: 50.00 Gy in 25 fractions 2
• Standard tangential photon fields using 6 or 15 MV photons 3, 5

Risks and Limitations of DIBH

Resource Implications

• DIBH requires longer simulation and treatment times compared to free breathing 8
• Additional staff training and equipment (surface guidance systems) are necessary 2, 8, 3

Patient Tolerance

• Some patients cannot maintain adequate breath-hold due to respiratory limitations, anxiety, or physical constraints 8
• Requires patient cooperation and ability to follow audio-video feedback cues 2, 3

Critical Implementation Points

Mandatory Cardiac Protection

• For all left-sided lesions, minimize cardiac volume in tangential fields regardless of technique used, as recommended by multiple guideline societies 6, 1
• Excess dose to heart or lungs through tangential irradiation must be avoided 6

Quality Assurance

• Delineate all cardiac substructures (heart, left ventricle, LAD) on both DIBH and free breathing scans for comparison 3
• Use dose-volume histogram analysis to verify cardiac and lung dose reduction 2, 4, 3
• Intrafractional 3D position monitoring ensures breath-hold reproducibility 3

When DIBH Cannot Be Used

• If patient cannot tolerate DIBH, proceed with free breathing technique using meticulous cardiac avoidance 8
• Ensure lung exposure remains ≤3-3.5 cm to minimize pneumonitis risk 6, 7
• Consider higher energy photons (≥10 MV) for large-breasted women to improve dose homogeneity 6