Phase 1-2 Study of Prone Hypofractionated Accelerated Breast and Nodal Intensity Modulated Radiation Therapy

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Prone positioning in radiation therapy (RT) for breast cancer reduces dose to the heart and lungs.
• Its application for regional lymph node treatment is less established than for whole breast irradiation.

Purpose of the Study:

• To evaluate the safety and efficacy of prone positioning for hypofractionated radiation therapy (RT) including regional lymph nodes in early-stage breast cancer.
• To assess acute and late toxicity, dosimetric feasibility, and oncologic outcomes.

Main Methods:

• A phase 1/2 trial treated 97 patients with stage IB-IIA breast cancer with 40.5 Gy in 15 fractions to the breast/chest wall and regional lymph nodes in the prone position.
• Primary endpoints included toxicity and dosimetric feasibility; secondary endpoints included resimulation rates and late toxicity.
• Oncologic outcomes such as local recurrence, disease-free survival, and overall survival were assessed at a median follow-up of 8 years.

Main Results:

• 92 out of 97 patients were treated prone; no acute toxicities greater than grade 2 were observed.
• Excellent dosimetry was achieved for the breast, nodal target volumes, heart, and lungs.
• At 8-year follow-up, local recurrence was 2%, with 8-year disease-free survival at 86% and overall survival at 91%.

Conclusions:

• Prone hypofractionated nodal radiation therapy is a safe and effective treatment for early-stage breast cancer.
• Low toxicity and excellent long-term oncologic outcomes support its use in clinical practice.