Whole breast radiotherapy in the lateral decubitus position: a dosimetric and clinical solution to decrease the doses...

Area of Science:

• Oncology
• Radiotherapy
• Medical Physics

Background:

• Large breasts present unique challenges in radiotherapy planning and delivery.
• Accurate radiation targeting is crucial for effective breast cancer treatment while minimizing side effects.

Purpose of the Study:

• To evaluate whole breast 3D-conformal radiotherapy (RT) in the isocentric lateral decubitus (ILD) position.
• To report the acute toxicity profile of patients treated with ILD for early-stage breast cancer.

Main Methods:

• 56 patients with large breasts and early-stage breast cancer underwent ILD whole breast RT.
• A dose of 50 Gy in 25 fractions was prescribed, with an optional 16 Gy boost to the tumor bed.
• Dosimetry and acute toxicity (NCI CTC v3.0) were analyzed weekly.

Main Results:

• The treatment was well-tolerated, with Grade 1 and 2 dermatitis in 37.5% and 58.9% of patients, respectively.
• Excellent dosimetry was observed, with extremely low doses to the ipsilateral lung and heart.
• Average mean lung dose was 0.96 Gy, and average mean heart dose was 1.35 Gy for left-sided tumors.

Conclusions:

• Isocentric lateral decubitus whole breast radiotherapy offers an excellent dosimetric profile for patients with large breasts.
• This technique is well-tolerated and demonstrates a favorable acute toxicity profile.
• ILD RT is a viable option for early-stage breast cancer in patients with large breasts.