Dosimetric and Secondary Cancer Risk Comparison after Radiation Therapy for Breast Cancer with Three-Dimensional...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Adjuvant radiotherapy is crucial for breast cancer treatment post-mastectomy.
• Assessing secondary cancer risk is vital in radiation therapy planning.
• Comparing helical therapy (HT) and three-dimensional conformal radiotherapy (3D-CRT) is essential for optimizing patient outcomes.

Purpose of the Study:

• To compare dose distribution and excess absolute risk (EAR) of secondary cancers.
• To evaluate HT versus 3D-CRT in patients with left breast cancer undergoing mastectomy and adjuvant radiotherapy.

Main Methods:

• Dose metrics (Dmax, Dmean, V5, V10, V20, V30) were extracted from treatment planning systems for both HT and 3D-CRT plans.
• Organ equivalent dose (OED) and EAR were calculated using dose-volume histogram (DVH) data.
• Comparison focused on critical organs like the heart, lungs, thyroid, esophagus, and contralateral breast.

Main Results:

• HT demonstrated lower maximum doses (Dmax) to the heart, spinal cord, and ipsilateral lung.
• 3D-CRT showed lower Dmax for the thyroid, esophagus, contralateral breast, and lung.
• HT resulted in higher OEDs and EARs for the contralateral breast and lung, while 3D-CRT led to higher OEDs/EARs for the ipsilateral lung.

Conclusions:

• HT and 3D-CRT offer distinct advantages in organ sparing for breast cancer patients.
• HT excels in protecting the heart and ipsilateral lung; 3D-CRT is superior for the contralateral breast and lung.
• Individualized treatment decisions are necessary, balancing radiation therapy technique efficacy with secondary cancer risks.