SBRT for centrally localized NSCLC - What is too central?

Area of Science:

• Radiation Oncology
• Thoracic Oncology
• Medical Physics

Background:

• Current guidelines recommend stereotactic body radiotherapy (SBRT) for medically inoperable stage I non-small-cell lung cancer (NSCLC).
• SBRT demonstrates excellent outcomes and toxicity profiles for peripheral lung tumors.
• The use of SBRT for centrally located lung tumors remains controversial due to limited evidence.

Purpose of the Study:

• To evaluate current clinical practices for SBRT of centrally located lung tumors.
• To identify common fractionation schedules employed for central lung tumors.
• To determine commonly accepted contraindications for SBRT in central lung tumors.

Main Methods:

• A two-part questionnaire was administered to centers within the DEGRO working group on stereotactic radiotherapy (Germany and Switzerland).
• The questionnaire gathered general center information and specific details on SBRT for central lung tumors, including case examples.
• Participants reviewed CT and PET imaging for nine primary NSCLC cases to assess treatment indications.

Main Results:

• Twenty-six centers participated; most were academic and offered SBRT for lung tumors.
• 88% of centers had experience with SBRT for central lung tumors, with half treating over ten cases in five years.
• Common fractionation involved 48-60 Gy in eight fractions. Tumors <4 cm and >2 cm from the main bronchus were widely indicated for SBRT.

Conclusions:

• SBRT for small (<4 cm) early-stage NSCLC is a common indication within the DEGRO group when tumors are at least 2 cm from the main bronchi.
• Prior pneumonectomy or adjacency to hilar/mediastinal structures were not universally considered contraindications.
• Prospective clinical trials are expected to clarify the role of SBRT for larger and more centrally located tumors.