Pulmonary effusion is a manifestation of advanced stage lung cancer. Once pulmonary effusion appears, it is advanced stage lung cancer, also known as stage IV lung cancer, which is usually bloody pleural effusion. For lung cancer combined with pleural effusion, local infusion of chemotherapy cisplatin, bleomycin or anti-tumor angiogenic drugs such as Endo can be used on the basis of adequate drainage, together with systemic treatment for lung cancer, such as chemotherapy, immune checkpoint inhibitor therapy or targeted therapy, etc. All in all, once lung cancer appears as fluid in the lung, there is no way to cure lung cancer in advanced stage through radical surgery, only local treatment plus systemic treatment.