In this article, I will explore the complexity of lung cancer and why it is classed as one of the most deadly cancers. As well as this, I will explain how different types of lung cancer are classified depending on the cells present in tumours and how the classification affects the treatment a patient is given. Furthermore, I will look at the current treatments for lung cancer and how they are used. And last but not least, I will explain what Circulating Tumor Cells (CTCs) are and how they may be able to help scientists diagnose and treat lung cancer in the near future.