Abstract
Lung cancer is the leading cause of tumor-related death in the world. Duodenal metastasis from lung adenocarcinoma is an exceptionally rare occurrence and is often asymptomatic. Currently, there are no FDA-approved, well-defined treatment guidelines for this patient subgroup, and clinical studies in this area are scarce, limited to several case reports. Further investigation is needed to identify suitable treatments for this group. Here, we present a case of lung adenocarcinoma with duodenal metastases in a patient who exhibited a notable clinical response to immunotherapy over 39 months. Due to the limited data available on duodenal metastases from lung adenocarcinoma, this case highlights the challenges faced by clinicians in managing such cases and provides new ideas for future management of the disease.