Help my father in law get surgery

My father in law was diagnosed with lung cancer last October. He had the surgery and was doing well. Couple months later he found out he had a Brain Tumor. They did their Kemo and radiation. Decided everything was ok for the time being. Well we just got word the brain tumor is growing and they’ve decided to do surgery. Well because of his restrictions form the lung surgery he was fried from his job that had insurance. Now he has his brain surgery on January 7 2019. They told him he needs $4,000 just to get the surgery. Please if anyone can help. He needs the surgery.