Radiation therapy is traditionally thought to suppress the immune system. However, it may also stimulate immune cells that can fight against tumor growth. A recent study found that increased levels of the immune cell proteins CD4 and CD8 correlated with improved survival in non-small cell lung cancer (NSCLC) patients who had received radiation therapy after tumor removal. The results suggest that immune cell protein levels could be used to help determine prognosis for patients receiving such "adjuvant therapy."