Cancers that begin in the lungs are divided into two major types, non-small cell lung cancer and small cell lung cancer, depending on how the cells look under a microscope. Non-small cell lung cancer generally spreads to distant organs more slowly than small cell lung cancer. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are three types of non-small cell lung cancer. It is important to find out what kind of lung cancer a person has. The different types of carcinomas, involving different regions of the lung, may give rise to different symptoms and are treated differently.
Lung cancer takes many years to develop.
With continued exposure, more abnormal cells appear. These cells may be on their way to becoming cancerous and forming a tumor. The symptoms of the cancer vary depending on several factors, including where in the lung the tumor is found. The cancerous area may bleed when a person coughs. If the tumor grows larger, it may gradually fill the bronchus so that air can't pass in or out.