Stage 4 non-small cell lung cancer is considered to be the most severe and advanced form of lung cancer. Around 40% of the people who are found to suffer from lung cancer are already in this stage by the time experts find signs of the disease within their system. This late stage of lung cancer cannot be cured, but it can be treated through a range of systems. Many clinical trials are already in progress, which allow experts to look at new solutions to improve the survival rate of their patients.