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Updated: Aug 6, 2026
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Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
First Measurement: Proactively Sparing the Immune System During SBRT to Early-Stage Lung Cancer-A Randomized Phase II
Krishni Wijesooriya1, Cam Nguyen2, Mark R Conaway3
1Department of Radiation Oncology, University of Virginia, 1300 Jefferson Park Ave, Charlottesville, VA, 22908; Department of Physics, University of Virginia, 382 McCormick Rd., Charlottesville, VA 22904.
Summary
Optimized radiation therapy sparing immune-rich organs significantly preserves lymphocytes in early-stage NSCLC patients, reducing lymphopenia without compromising safety. This approach may improve survival outcomes compared to standard treatments.
Area of Science:
- Radiation Oncology
- Immunology
- Medical Physics
Background:
- Radiation Therapy (RT) can suppress anti-tumor immunity by causing Radiation-Induced Lymphocyte Kill (RILK).
- Minimizing RILK is crucial for enhancing tumor-specific immunity.
- Current RT guidelines may not sufficiently protect immune-rich organs.
Purpose of the Study:
- To assess the effect of dose reduction to immune-rich organs beyond standard criteria on RILK in early-stage NSCLC patients treated with SBRT.
- To evaluate the impact of optimized SBRT on lymphocyte counts and adverse events.
Main Methods:
- A single-institution phase-II randomized trial involving 51 early-stage NSCLC patients.
- Patients were randomized to optimized-SBRT (dose reduction to blood, bone marrow, lymph nodes) or standard-SBRT.
- Peripheral blood was collected at multiple time points for Absolute Lymphocyte Count (ALC) analysis.
Main Results:
- Optimized SBRT achieved significant dose reductions to heart, lymph nodes, and thoracic vertebrae compared to standard SBRT.
- Patients receiving optimized SBRT showed a significantly smaller decrease in ALC post-treatment (13.4% improvement).
- Grade 3 or higher lymphopenia was absent in the optimized arm, versus 15.4% in the standard arm. Dose to immune-rich organs correlated with RILK.
Conclusions:
- Significant dose reductions to immune-rich organs are achievable in lung SBRT with comparable safety.
- Optimized SBRT markedly preserves lymphocytes compared to standard-of-care.
- This approach shows potential for improved survival outcomes.