This study is being done to find out whether features of the thymus gland can predict a common side effect of radiation therapy for lung cancer called radiation-induced lymphopenia.
We will include adults with stage III non-small cell lung cancer (NSCLC) who are scheduled to receive curative radiation therapy to the chest, with or without chemotherapy.
Before, during, and after radiation therapy, we will measure:
The dose of radiation that reaches the thymus gland (based on each patient's treatment plan)
The size and shape of the thymus gland (using CT scans taken for radiation planning)
The number of lymphocytes (a type of immune cell) in routine blood samples
The main goal is to see if certain radiation doses to the thymus, or a smaller thymus size, can predict severe lymphopenia. We will also check whether lymphopenia affects patient outcomes such as infections or survival.
This is an observational study (no added treatment or drug) - patients will receive their standard radiation therapy as planned by their doctor. The study only collects and analyzes data from standard scans and blood tests.
Potential benefits: Findings may help doctors design "immune-sparing" radiation plans in the future to reduce lymphopenia. Potential risks: There are no additional risks beyond standard radiation therapy, as this study does not change your treatment.