Central-boost Ablative Radiation Therapy for Solid Tumors: Study Protocol of a Single-arm, Phase II Trial (CBART)

Area of Science:

• Radiation Oncology
• Medical Physics
• Clinical Oncology

Background:

• Stereotactic body radiation therapy (SBRT) is common for advanced tumors, but ablative doses can be problematic for large or gastrointestinal-adjacent tumors.
• Partial irradiation strategies are being explored to manage these complex cases.
• Central-boost ablative radiation therapy (CBART) was developed to deliver higher doses to the tumor center while maintaining lower doses at the margins.

Purpose of the Study:

• To assess the efficacy of CBART in patients with large tumors or tumors adjacent to the gastrointestinal tracts.
• To evaluate the one-year local control rate as the primary outcome.

Main Methods:

• A prospective, single-arm, phase II trial was conducted.
• Patients received CBART, with a central core GTV (cGTV) comprising 50% of the GTV, and a planning target volume (PTV) with a 2-5 mm margin around the GTV.
• Prescription doses were 30-45 Gy/5f to the tumor margin and 120%-150% of the margin dose to the cGTV, with 90% coverage of PTV and cGTV.

Main Results:

• The study aimed to determine the one-year local control rate.
• Subsequent systemic therapies were administered based on tumor characteristics.

Conclusions:

• CBART may enhance local control for large or gastrointestinal-adjacent tumors by delivering ablative doses to the hypoxic core and lower doses to the margins.
• Further research is needed to confirm the clinical benefits of CBART.