Clinical Scorecard: Assessment of Organs at Risk (OARs) During Whole-Breast Radiation Therapy: A Comparative Analysis of Prone and Supine Positions with Deep Inspiration Breath-Hold Techniques from a Prospective Study Subgroup

At a Glance

Key Highlights

• Whole-breast irradiation improves breast cancer-specific survival but exposes heart and lungs to radiation, increasing risk of cardiac injury and secondary cancers.
• Deep inspiration breath-hold (DIBH) reduces mean heart dose, especially in left-sided breast cancer; prone positioning reduces lung exposure.
• This prospective subgroup analysis compares supine free-breathing, supine DIBH, and prone positioning techniques for both left- and right-sided breast cancer.

Guideline-Based Recommendations

Diagnosis

• Use RTOG guidelines for target and OAR contouring during radiotherapy planning.
• Perform CT simulation scans in supine free-breathing, supine DIBH, and prone positions for comprehensive dosimetric assessment.

Management

• Prescribe hypofractionated radiotherapy: 49.5 Gy in 15 fractions to boost PTV and 43.5 Gy in 15 fractions to PTV.
• Use 3D-CRT hybrid IMRT/VMAT techniques to optimize target coverage and minimize OAR doses.
• Select patient positioning (supine FB, supine DIBH, prone) based on cardiopulmonary function, breath-hold ability, and dosimetric benefits.

Monitoring & Follow-up

• Evaluate dose-volume parameters for heart, LAD, RA, ipsilateral lung, and contralateral breast using dose-volume histograms.
• Prioritize minimizing mean heart dose and lung exposure during plan optimization.
• Use real-time 3D surface imaging (e.g., AlignRT) to ensure reproducible patient positioning and breath-hold stability.

Risks

• Radiation-induced cardiac injury and secondary lung cancers are dose-dependent risks associated with whole-breast irradiation.
• Inadequate breath-hold or positioning may increase radiation exposure to OARs.
• Patients with poor cardiopulmonary function or inability to maintain breath-hold may not be suitable for DIBH.

Patient & Prescribing Data

Breast cancer patients undergoing breast-conserving therapy with left- or right-sided tumors

Hypofractionated radiotherapy with combined 3D-CRT and VMAT techniques provides optimal target coverage while sparing heart and lung; patient positioning and breath-hold techniques should be individualized based on tolerance and dosimetric advantages.

Clinical Best Practices

• Screen patients for cardiopulmonary function and breath-hold capability before selecting DIBH technique.
• Use multiple CT simulations in different positions to identify optimal plan minimizing OAR doses.
• Apply RTOG contouring guidelines and include safety margins around coronary arteries for accurate dose assessment.
• Prioritize heart and ipsilateral lung dose reduction during treatment planning.
• Conduct independent plan reviews by senior radiation oncologists or physicists to ensure quality and safety.
• Utilize real-time surface imaging systems to maintain reproducible patient positioning and breath-hold during treatment.

References

• ClinicalTrials.gov NCT05609058
• Radiotherapy Oncology Group (RTOG) guidelines
• Wang SL et al. hypofractionation scheme