Previous studies indicate that the overall survival rate (OS) of PSC patients is not significantly associated with factors such as race, age, sex, smoking history, tumor size, pleural invasion, or lymph node metastasis,[29,39,40] but is dependent on histological subtype, tumor stage, distant metastases, pathological stage, vascular invasion, and mutations in genes such as programmed cell death-ligand 1(PD-L1), TLG-P, and KRAS. The gene discussed is KRAS; the disease is metastatic malignant neoplasm in the lymph nodes.