Hello, Stage 4 lung cancer is an advanced disease. At this stage, the cancer is metastatic—meaning it has spread from the lung, where it originated, to other parts of the body. Recurrent infections are seen in that stage. The following are probable options to treat the infection: 1) Oral or intravenous antibiotics 2) corticosteroid inhalers 3)oxygen inhalation if necessary 4) bronchodilators 5) if breathing difficulty is present, and saturation is low, assisted ventilation devices like non invasive ventilation like CPAP can be initiated 6) Intravenous fluids to maintain hydration From the symptoms you mentioned I suspect your friend is suffering from pneumonia. The infection can be cured completely. As he also has lung cancer it takes more time than that in a normal patient. The outcome in a lung cancer patient depends upon the following: 1) Type of cancer 2) Stage of cancer 3) Metastasis or spread to other organs is present or not 4) Age of the patient 5) Comorbidities of patient like diabetes, congestive heart failure etc. 6) Smoking 7) Performance status of individual which means ability of the individual to perform his regular activities The prognosis of a stage 4 lung cancer is: 5 year survival rate of stage 4 non small cell cancer is 7% 5 year survival rate of small cell lung cancer stage 4 is 3% Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Pallavi M., Anesthesiologist