NCCN Guidelines for Patients® | Lung Cancer - Non-Small Cell Lung Cancer

10 NCCN Guidelines for Patients ® : Lung Cancer – Non-Small Cell, 2018 1 Lung cancer basics Cancer’s threat | Review Mutations Cells have a control center called the nucleus. The nucleus contains chromosomes, which are long strands of DNA ( d eoxyribo n ucleic a cid) tightly wrapped around proteins. See Figure 3 . Within DNA are coded instructions for building new cells and controlling how cells behave. These instructions are called genes. There can be abnormal changes in genes called mutations. Some types of mutations that are linked to cancer are present in all cells. Other mutations are present only in cancer cells. Mutations cause cancer cells to not behave like normal cells and, sometimes, to look very different from normal cells. Cancer’s threat When needed, normal cells grow and then divide to form new cells. When old or damaged, they die as shown in Figure 4 . Normal cells also stay in place. Cancer cells don’t behave like normal cells. Cancer cells differ from normal cells in three key ways. Mass of cells Cancer cells make new cells that aren’t needed. They don’t die quickly when old or damaged. Over time, cancer cells form a mass called the primary tumor. Invasion The second way cancer cells differ from normal cells is that they can grow into surrounding tissues. If not treated, the primary tumor can grow through an airway. It can even grow into nearby structures. This is called invasion. Lung cancer can invade another bronchus or the pleura. Cancer cells can replace so many normal cells that is it hard to breathe. Metastasis Third, unlike normal cells, cancer cells can leave the lungs. This process is called metastasis. In this process, cancer cells break away from the tumor and merge with blood or lymph. Then, the cancer cells travel in blood or lymph through vessels to other sites. Once in other sites, cancer cells may form secondary tumors and cause major health problems. The sites to which lung cancer travels are listed in Part 3. Review † † The lungs help the body get the air it needs to live. † † The lungs are made of many small airways and sacs. † † Lung cancer often starts in the cells that line the airways. † † Cancer cells form a tumor since they don’t grow and die as normal cells do. † † Cancer cells can spread to other body parts through lymph or blood.