A patient with metastatic non-small cell lung cancer who received pembrolizumab monotherapy after stereotactic body radiotherapy had progression-free survival of nearly 5 years: a case report.

Lung cancer is a malignancy with the highest morbidity and mortality in the world. Radiotherapy, chemotherapy, targeted therapy, and immunotherapy have been widely used to treat metastatic non-small cell lung cancer (NSCLC). Stereotactic body radiotherapy (SBRT), also known as stereotactic ablation radiotherapy (SABR), can precisely deliver a high dose of radiation to a target in a limited area. SBRT has been established as the standard treatment for patients with early NSCLC who are unsuitable for operation or refuse surgery and patients with oligometastatic NSCLC who are not suitable for surgery. As an immunologic agent, pembrolizumab has been approved to treat metastatic NSCLC in certain countries, including China and the United States. Increased tumor proportion score (TPS) can reduce pembrolizumab's immunotherapeutic effect, while SBRT can reduce TPS and enhance immunotherapy efficacy. However, there have been no reports in China on metastatic NSCLC patients who have received pembrolizumab monotherapy after stereotactic body radiotherapy (SBRT). Here, we present a case of progression-free survival (PFS) of nearly 5 years with pembrolizumab monotherapy after SBRT for metastatic NSCLC. This case is the patient with the most prolonged medication duration and who experienced the most efficacious treatment among the patients with metastatic NSCLC reported in the Chinese literature.