Additions and subtractions of radiotherapy in patients with oligometastatic non-small cell lung cancer under the era of immunotherapy

Oligometastatic non-small cell lung cancer (NSCLC) is a distinct subtype characterized by a limited number of metastatic lesions. Radiotherapy (RT) is vital in treating NSCLC. However, the role of RT should be investigated further as the treatment of NSCLC has been revolutionized by immunotherapy. In this review, we aimed to explore"additive" and "subtractive" strategies involving RT for treating oligometastatic NSCLC. In additive strategies, the synergistic effects of combining RT with immunotherapy are emphasized, which can improve local control and enhance systemic immune responses. In contrast, subtractive strategies involve limiting or eliminating RT in specific patient subgroups, especially in those who respond appropriately to only immune checkpoint inhibitors. This minimizes toxicity and improves the quality of life. We provided insights into the efficacy and safety of these strategies, while considering factors including patient selection, treatment sequence, radiation dose, and fractionation schedule. Furthermore, we discussed the challenges and unresolved issues. In this review, we summarized the latest clinical trials and advances in research to provide the scientific basis and practical guidance for personalized RT strategies for treating oligometastatic NSCLC when receiving immunotherapy.