Immune-Sparing SBRT Optimization in Early-Stage NSCLC
Stereotactic body radiation therapy (SBRT) can be effective for patients with early-stage non-small cell lung cancer (NSCLC) who cannot undergo surgery. However, sometimes cancer can return after treatment. Clinical trials are now testing whether adding immunotherapy after SBRT can lower that risk. Immunotherapies activate a patient's own immune cells to hunt down remaining cancer cells, so their success depends on how many healthy immune cells survive after SBRT. When SBRT is used against lung tumors that are adjacent to the heart, this may expose more immune cells to radiation than when used against tumors in other locations. Our group has researched the impact of this exposure, called the Effective Radiation Dose to Immune Cells, or EDIC, using measurements already captured during routine treatment planning. In a cohort of 282 patients with early-stage NSCLC treated with SBRT, those with higher EDIC had substantially worse five-year survival than those with lower EDIC. This proposal asks three questions: whether EDIC predicts the drop in immune cell counts seen after treatment, whether that drop helps explain the survival difference, and whether radiation plans can lower EDIC without sacrificing tumor control. If EDIC proves to be both predictive and modifiable, it could become part of routine treatment planning.
